Holy crap.
Ulic I appreciate the effort you went to for that crazy reply but sounds like the gist of what you're saying is that "if you're not open to the possibility that she could at any time cheat on you, you will get hurt one day, real bad". Again, I am going to have to take that risk. I just wouldn't feel like I was in a proper, decent relationship if I always had to keep in the back of my mind "she could cheat on me any time, and today could be the day." No, screw that lol. Seriously would rather be single.
Another common theme in what you're saying is "faithfulness is an illusion. one person belonging to one another is an illusion. Your gf is not an object, she has free will and she can and will get with another guy". See, but it's because a person has free will and can make their own choices that it's so significant to me that they manage to not mess around. It's the sacrifice that YES, you could cheat on your SO and get away with it, but you don't, because you gave your word that you wouldn't, and your word means something. For me, a major part of a relationship is having a level of trust with someone right up there with your best friends and one day, exceeding that with your family members. Could you really be as close to someone without being able to let go all the way, never having to doubt them?
I believe you also said that when you get in a relationship, you would never promise to not cheat on her. Because you're a man of your word. See, that's fine then. All I'm asking is that whoever I'm with makes that same statement, that they won't promise to not go off and mess around with another guy. As long as I know that up front, there are no issues. That's the whole reason OP is a scumbag, that his gf has no idea this is going on, and the longer this goes on, the more traumatized she's going to be when she finds out.
Edit: I feel bad for not addressing more of what you said, so here's more:
So you said you're out there looking for love, you're looking for that 12/10, who will be THE one, the perfect one for you. See, I'm not looking for my 12/10 though. I'm trying to find the 8/10 who makes me happy and I can get along with. This is hard enough. I have eventually always found something about a girl that is enough that I realize I can't live with for the rest of my life. Maybe I'm picky I dunno. Sometimes this happens quickly, and sometimes it takes years. But "good enough" IS my 12/10. I know what you're thinking, I'll address it in my next point.
You gave me an example. You said what if I show up to some party and I meet some girl who's much hotter than my gf, and she's just better in every way that matters to me. First off, past a certain point I don't really care how hot a girl is anymore. If I look at her and I think to myself "hey, she's pretty." Good enough. Any extra beyond that is just more short-term lust: physical attraction that has no bearing in the long run imo. Where I get picky is whether she can keep up with me intellectually (or whether she runs circles around me), whether she's interesting and fun to talk to, whether she gets me and my particular sense of humor. So if she's actually 10x better in every category than my gf, and I see her on a couple more occasions and it's consistent and wasn't just the drinks talking, then you know what happens next? I break off all contact because I realize what's happening, and I think long and hard about how often this happens, and whether my current gf really is my 8/10 if this keeps happening. If I decide to go for this other one, then I drive myself down to my gf's place, man up, and tell her "I need you to break up with me."
Edit2: Read more of what you said, I think I see where you're coming from..
You say it's an illusion that you've found "the one", because chances are, you can exactly duplicate what you have with any number of other people, especially if you haven't dated like mad like Ulic has. You know what, I agree. I absolutely agree with this, but what I would say to you is that if you're constantly looking for someone better, there will ALWAYS be someone better out there. When does it stop? When are you going to finally be satisfied? And btw, there are countless other guys out there looking for the same thing, and the hotter this girl is that you've just found, the more likely she'll be taken away from you by others. Guys who are better than YOU (maybe not better than you at typing epic 5-page replies on Revscene though, you'll always have that one

).
Am I getting too old that all I want is "good enough, let's not go nuts"? Is it weird that I don't need whoever I'm with to be exceptionally hot, exceptionally accomplished, exceptionally this and that, in order for myself to be happy? Especially at the cost of having to cheat? I don't think I should have to be so dependent on being with literally Ms. Perfect to have a good life. If we make each other happy, and if they can keep up with me, seriously.. good enough. =)