<human>: Can you summarize the given text in a few sentences?

I just recently started dating a girl I know, and soon found out that she had just recently broken up with her boyfriend of a year and a half. I started dating her about a month or so after she broke up with this guy. 

At first I was a little worried that I was a rebound boyfriend, but she assured me that I wasn't. We went on a few dates and hung out at each other's houses, until one day she got a call from her ex, who basically asked for her back. She said no, and life went on. Back story, her ex is apparently a very nice guy, she has never said anything bad about him at all.

Recently, she has decided she wanted to be friends with her ex, assuring me that friends was all that it was. I'm not really sure what to do here. I've only been dating her for around three weeks, and I feel kind of weird that she is back talking to her ex, whom she dated for over a year. I talked to her about it, but she seemed adamant that they were only going to be friends.

What's your guys' opinion on this?
<bot>: Girlfriend is talking to her ex again, I feel kind of weird, she assures me it's just a friendship.