Hi.
I'm new here so I hope I'm making this post in the right place.

I was in a relationship with my girlfriend from last year November. I noticed that she was a flirt by nature before we got together but I thought it wouldn't bug me too much. In late January this year, she left her facebook page open on my computer and i discovered heavy flirting with this dude that used to be her neighbour a while back to the point of having pet names for each other like "babe" and so on. When i first discovered about the facebook messages, I didn't confront her about it, instead i waited to see if she would be straight with me at some point. I discovered a bit later that she had given him her phone number and they continued flirting via text till some time in late February when I confronted her and told her that I had known about it for almost a month.

We fought quite a bit and she was very apologetic but I told her that by virtue of how I had found out about that, I would have problems trusting her. We stayed together but have been fighting on and off a lot since then and I have honestly initiated many of them because I have never quite gotten over that incident. It felt like a big betrayal to me even though I knew she was rather flirtatious before we began and know that she loves me a lot. About one month ago, we broke up but have since had sex a few times and hang out a few times too.

Currently we are still broken up. I monitored how she behaved since that incident earlier on in the year and she seems to have reduced the flirtatious part of her quite a bit since then and seems to have changed in that respect. I know that she wants to get back together with me. However, whenever I begin to see some hope and feel like I can trust her again, I remember how I found out about it all, and that she hid it from me and acted normal, without any signs of guilt or remorse for over a month, until I confronted her, and that makes me feel like I will never be able to fully and completely trust her. I have wanted to break up with her because of this trust issue but somehow we always end up back together.

My question is, am I overreacting to that incident and expecting too much when I expect her to always put all guys in their place when they hit on her?? I feel like out of respect for me, she should have drawn the line when the guy began to openly flirt with her and call her pet names that I called her.

And is it unreasonable that my feelings aren't changing despite the fact that I have actually noticed a change in the distance she keeps from other guys? And I want to take that fact into consideration but I just cannot forget particularly how I found out about that incident early in the year and the fact that she wasn't going to reveal that to me.

Any answers and/or advice will be sincerely appreciated and any questions regarding the information above are welcomed. Thanks.