About 6 weeks ago, 2 months ago, she tells me the last guy she had a serious rel'ship with, they broke up 2 years before we met, (a guy she dogged whenever she mentioned him, but it's not like she always brought him up, when we would talk about past experiences with exes she would compare me favorably to him) emailed her wanting to get back together, and she emailed him back and said she was with me now and too bad, so sad. Then she says that she's had guys tell her they loved her before, that they would marry her before, and nothing lasted beyond a year, and she wanted to know if I was serious. And I assured her that I was, and she says "Good. I hate him. You're the one I want to be with."
I don't like the idea of her talking to exes at all, but the way it was presented, he contacted her, not the other way around, and based on her account, there was nothing to really be mad at her for. I would have preferred she just ignore him, but emailing him to tell him that he she was involved with somebody else could be interpreted as a courtesy. And if you were going to cheat on me, why would you even mention that you were talking to exes? The way our rel'ship was going, I would be none the wiser if she simply kept her mouth shut, and she didn't have much physical opportunity to do so, since we were together every Friday-Sunday and then another night during the week.
I'm not ruling it out, of course, but it doesn't seem likely either.