Thoughts on mistakes

Do we repeat ourselves? Do we learn from our history?
I like to think we do. I like to think I do. But it seems I don't, because I get tangled in these situations over and over.
Let's talk relationship mistakes.
I get involved with someone, I give it all... I get screwed. I allow myself to think this is gonna work out, I mean, this time we'd been together for almost 3 years after knowing each other and liking each other for 7 years... I really wanted this to be the time it worked, I even put a down-payment on a house... that I now will live in alone with my dog. So, what happened? Trust issues. That's what happened. She couldn't trust me because of her own doubts and fears, not because I'd done anything.
When we first started dating, another girl, a friend, kissed me. I was so startled and I didn't want to make a big deal out of it, so I didn't tell my girlfriend (my mistake) and then I hid it from her for months and she found out later. I paid for that mistake until today it seems. From that point on she felt she couldn't trust me even though I never saw that girl again, I shunned all the friends she was jealous of and I just worked hard to make her see I only wanted her.(my mistake?)
I gave her everything I had and more. And I really thought we'd worked things out and things were shaping up, until she told me yesterday she'd started having feelings for someone else. A friend of US who knows we've been together who has seen us, who knew we were having trouble. They started texting a week ago, and he started flirting with her because "he knew we were having problems and she felt the same way he did"... so now she's confused. Bull.Shit. He's not nice. He's not a good person. Because saying that he never gets in the way of other people's relationships and then doing EXACTLY THAT doesn't make you a good person. And I hope she finds out before she gets hurts.
The sad thing?
I love her.
With everything I am.
But I know this won't work out now, because she made a decision when she chose to flirt with him and to take a "time out" from our relationship to think things through. And I know she's gonna have something with him, I have no doubts about that because I can tell that's what she wants. And how can I take her back after that? I already did it once before and I ended up being really hurt and feeling stupid, and I won't do that again. No matter how much I love her or how much I want to be with her. I need to accept this is over. But I can't because it hurts too much to think I'll be alone now. Again. I can't even begin to think about starting anything with anyone else, letting anyone else in. It's just not worth it anymore.
But instead of wallowing in my own sadness, I've decided to take the calm way out. Just wish happiness and all the best to her because above all, I want her to be happy and I really hope she finds that happiness I couldn't give her or she couldn't find with me.

Maybe it means I've learned? We'll see..