<human>: So everything's pretty great. I'm in probably my best relationship of my (relatively young) life. We love each other and are a regular subject of #relationshipgoals, etc. Except for one thing.

The beginning of our relationship began with her falling for me while with her previous boyfriend. We met in college and her boyfriend was back home, so distance was obviously a factor. She left him basically for me, which I felt mixed about, but what's done is done. 

Now summer comes and she is hanging out with him again. A trip to a tea shop to catch up, a run together, various casual hang outs. She assures me I have nothing to worry about, and a good part of me believes her. She has kept in touch with pretty much every ex and remains friends with them. But am I wrong in assuming her ex just wants her back and this is his way back in? 

I have some pretty hefty insecurity issues about these things (I set myself up for disaster with this relationship, I know), and she knows this. Should I approach her and discuss this more? Should I insist or suggest she cuts off contact with him? Part of me thinks this is unreasonable and the other part thinks this has gone on long enough. 

I know she loves me, and I'm not sure that's really the problem, it's just that this hurts me and I wonder if I'm being unreasonable or caught up in the story. Perspective anyone?

Summarize the given text in a few sentences.
<bot>: Girlfriend keeps hanging out with ex bf whom she left for me - Is my insecurity warranted and should I ask that she cuts off contact?