You didn't lose out to anyone but I get how you feel. Remember that thread I made about the guy who played me? That killed my confidence for a while but I'm just now starting to realize that holding on to this idea that there is this ONE person for us is destructive. There are many men out there with whom you will connect on an even deeper level than you did with this one man. I know it is hard for you to see it right now but which seems more likely? That in a universe of billions of people, this one "supreme being" is the only person with some magical capability to connect with you on a deeper level-- or that there are a whole bunch of men who can tap into your heart and connect with you in various ways?
Like you, I was so caught up in what I "lost" because I let my ego drive my emotions. I was too focused on feeling like I didn't win. I wasn't good enough. I wasn't chosen. That's crazy. I didn't lose anything. Instead, I was set free to love someone else who is more deserving. You've been set free. Open your heart to the possibility of loving someone else. If you need to heal first, do that. Therapy is a great start. Be good to yourself, and give yourself the love, compassion, and forgiveness that you've given others.
And enjoy your vacation. If couples make you feel bad, ignore them.
Shoot, that's what I do. It's still tough for me so when I'm feeling vulnerable, I avert my eyes and just enjoy the moment with no outside influences. I was at a show over the weekend and everyone was coupled up. I was determined to still enjoy myself so I closed my eyes and just became one with the music... like no one else was there. Fake it 'til you make it. You got this.