I'm lighting the firecracker.....
Is your friend really engaged to him or has she just moved in with him?
I'm only asking b/c I know a lot of females perpetrating fraud. They have to justify what they're doing and/or trying to pressure the guy to commit to more than he willing to do. So she goes around like oh he better get me a ring for my B-day, Valentine's, Christmas, and telling everybody she's engaged or getting engaged to said man. Meantime, in the real world he's just with her for now and has no plans to get engaged or married to her, but he's not telling her that cause she's in house booty. I'm not saying do it or not, but know what your doing and don't expect anything from it, b/c it is what it is and nothing more.
I have 2 friends this happened to girl and a guy. 1st the girl: they had sex on the 1st date, she wanted to move in and he was cool with that so they shacked up, but then she wanted a ring, marriage and stuff. She went around telling everybody she knew that they were engaged and going to get married to force him into it. Well let's just say she broke her face on that. He was not on that with her he just wanted a live in GF, period. So they broke up and 6 months later he married someone else. She also thought that having sex on the 1st date guaranteed that you were in charge of the relationship, of the man and used it to control men. She's my girl but she played herself.
2nd the guy: they had sex after they just met, no date yet, he was barely dating her a month when she busts out with, can we start looking at places to move together, and when he was like I'm still in school, she was like I might be pregnant, yada, yada. You know they broke up.
Did you ever watch SATC =Sex ad the City, it's very telling on how women and men interact, if you haven't watch the DVD's not the edited TV versions. Men think differently, period. If you watch it pay attention to the 2 female archetypes Samantha and Charlotte, Sam=is the alpha female who thinks and acts like a man. She has sex on the first date, sometimes at first site. But she's drinking the kool aid and she KNOWS what she's drinking. She doesn't pretend or front about it. She knows that he's not sticking around, not to be her BF, lover, fiancé, husband and she doesn't want that either. Charlotte is kind of neurotic in a cute way and desperately wants a husband but she's sexing everybody in the hopes of making him "the One". When she stopped obsessing over finding the one is when she found him.
It's not like he's so into you that he has to have you that first night, that's the women's version, the man is like dayum she's hot, I want some of that let me hit it. Don't think for a minute that he's thinking wow she's so beautiful, smart, this that and the 3rd, I better wife her up STAT, he needs some time to get to know you 1st for any of that to happen. I don't think it takes years either to get to know someone but 1st date sex=relationship, marriage, is the exception not the rule.