***I apologize for the length in advance***
WOW! Just reading what you ladies have gone through is really an eye-opener! But it's also encouraging too because you ladies eventually got away from these men who were "not quite right" and found better happier relationships afterwards.
I was a psychology major, so issues like these and mental disorders always interest me.
In answer to the OP's question....
Yes, I've experienced what mental illness in a SO can do to a person. I've experienced it by seeing what my mom has been through, and also from my OWN personal experience with an "ex".
My mom...
My mom is married to my stepfather who has been diagnosed as bi-polar and suffering from depression. He grew up with a horrible childhood.
That's another reason why it's good to ask guys how they grew up, or what their family dynamic was like, because it really does shape you as a person when you get older...whether you want it to or not.
Anyway, before he was even diagnosed, I would notice that he would change!! Like, he would do a "Dr. Jeckyl/Mr. Hyde" type of switch!!
One minute he would be very nice, fun, outgoing and lively, and then the next minute he'd be saying underhanded nasty things, his face would change to being mean/angry, or he would be very irritated! Of course, he didn't change within a minute...I'm just exaggerating, but his switch was such a stark contrast!
Eventually over the years, he has gotten help. He has gone to counseling, and has taken medication for his illness. Let me tell you, medication is WONDERFUL! He's like a totally different person! The "nice guy" that he could always be is finally there ALL the time. He doesn't have mood swings as often (if at all), and he just generally seems happier.
He seems a LOT more stable now.
However, make no mistake...it has not been an easy ride for my mom. They have seperated and reconcilled more than twice, and she has had a LOT of heartache, pain, and frustration over the years due to his illness. However, they are still trying! So, it just goes to show that sometimes things can work out if one partner has a mental illness, but THEY have to recognize that they have a problem, and get HELP. I don't think a healthy relationship can be had any other way.
My experience...
For me...I was dealing with an "ex" guy "friend" of mine who I really do suspect has some mental issues as well.
His behavior or issues don't seem to be as serious or glaringly obvious as what some of you ladies have experienced, but deep down I still think that he has some type of issues.
For one thing, he's
MOODY as all get out!
Any little thing can get him moody and in a bad mood. His moods tend to go up and down at the drop of a hat. One minute he can be smiling, the next minute he's upset. Or, he can go from being upset to being happy in less than 10 minutes. Hmmm....
Another thing...I feel like he needs women or female attention in order to feel whole/complete/worthy. But yet, he is so strange sometimes around women. For example, he's very nice-looking, and has a great build so women usually fall at his feet. He can flirt with you and make you feel like the only woman in the room, but at the next encounter he can ignore you or act like he barely even knows you!
I went through so much pain and heartache over him for years!!
I began to think whether or not I was going crazy!
Before knowing him I never had the types of feelings that I had. I even slipped into a mild depression while going through issues with him. Plus, I would see how he would act towards other women he was interested in and he'd be the same way. Almost EVERY single woman who was interested in, or who had a "thing" with him would end up mad at him in some form or some way. Hmmm...that's a RED flag!! I saw how he would get so angry and fight with a girl he was dating (IN PUBLIC!) and how he would treat her with disrespect. Sometimes he seemed like he was the nicest guy in the world, and other times he was the meanest.
I now see that he can flip on and flip off his personality depending on who is in the room or who else is around. He's like a chameleon! I don't really know his TRUE personality sometimes! It's so weird!
I think he kind of knew though that he had some type of problem or some form of depression or whatever, because whenever I would confront him with his behavior or actions, he would get all sweet and quiet and tell me that he was sorry and that he knew that he had to work on his personality and that "a lot of people" tell him that he's this way, etc. So, I think deep down he
KNOWS that there's something not quite right with him. Sometimes I honestly feel sorry for him, and other times I can't stand him lol.
To this day, I don't even know what's wrong with him! I don't know how to "diagnose" him lol...and I've spent
WAAY too much time analyzing and OVER-analyzing him. He's dating some other girl right now, and he seems a little more "normal" these days, but I still see signs that he's not quite right. I just wonder when or if his current gf notices his behavior. Every single girl that I have known him to be with always seems to end up "babying" him, or trying to take care of him somehow. It's like, he leads them to believe that he's helpless or needs so much consoling or what not. It's really a weird thing.
erplexed
I figure that he has some sort of depression mixed in with low self-esteem, insecurity, immaturity, ambivalence/emotionally unavailable and perhaps a little bi-polar disorder in there somewhere. His moods are very HIGH and low, and constantly changing. Anyway, whatever it is... I really do hope that somewhere down the line my "ex"/guy friend gets some help. If not by medication, then at least get some counseling. I think counseling would probably do him a world of good. He's in a relationship right now, but honestly I don't think he is emotionally capable of having a HEALTHY relationship. I think he needs more time and maturity. He really needs to take care of his inner demons first. I feel like he has a lot of pent up anger inside.
But the thing is, people have to recognize that they need help.
If there's one thing that this experience and the experience my mom has gone through has shown me, it's that I just want someone NORMAL...or at least a guy who has a pretty even personality. I don't want any guys who are UP and DOWN all the time. I've been on that rollercoaster before, and I say NEVER again!
It's sooo not worth it! I used to cry myself to sleep because of how that "ex" guy treated me! He had me second-guessing myself, and questioning my self-worth. He made me wonder if maybe I was being too harsh or was going crazy! He made me feel like if he was unhappy, it was because of something that I did. If he was happy, I was happy. But if he was upset...I felt like I was to blame. He knew how to cut me with a glaring look or a harsh word here and there.
He caused me so much pain and heartache. When he was nice, he was wonderful. Attentive, caring, sexy, and fun. But when he was his "other self" he was cold, distant, rude, mean, and hurtful.
Then, later on or a few days/weeks later he'd want to be all nice and apologize or be "normal" again. UGH!!
It was like he was making me go crazy! Like...am I the one that's nuts??
I don't want this type of relationship anymore.
I've also learned how to detect "red flags" in guys a lot better now.
Now days I'm MUCH more observant of a guy and his behavior...not only towards me, but towards OTHERS. I secretly watch a lot more now.
I just take it all in. If a guy isn't making me feel "right", or is treating me (or others) with disrespect, I don't just make excuses for his behavior now. These days I take that to be a HUGE glaring sign that maybe this guy is not the guy for me. I also pay attention to the little "voice" inside my head that tells me that something doesn't feel right. If it doesn't feel right, then chances are it's NOT right.
As women it's hard for us to not feel sorry for some men or try to "nurture" them because that's in our blood. Especially if you're a psych major like me. But now that I've healed more and more, I realize that I dont' want a guy that I "feel sorry" for. I'm a woman...so I want a
MAN...not a child. Now, it's one thing if you're married and your husband develops some kind of depression or illness. AFterall, marriage is for better or for worse. But I don't want to be dating some guy who I have to be trying to analyze, or help feel better all the time. It's too much work!
Oh..my..God above. SAME BLOODY THING!
It was always the world against him. He would do things and would NEVER be in the wrong, it was someone else's fault.
He touted himself to be so great and above others and said I was "perfect and ideal" for him since we were both on another plane of existence. 
Hmm...he sounds like he might have NPD (Narccissistic Personality Disorder).
It's hard having an unstable person in your life. 
.... for which I needed to be PUNISHED. 
