<human>: My boyfriend and I have been together for almost two years. We were broken up for about 6 months last year, and since we got back together, things have been amazing. (Long story short, there were some cold feet). I recently found out about the girls he slept with while we were apart. One of them is his most recent ex (3 year relationship). I was not with anyone while we were broken up. We've discussed it, and he has expressed many times that it meant nothing, that it was just sex and didn't do much for him. 
I in no way think that he will cheat on me, or think that being with someone else while we were broken up could be considered as such. But knowing that he was intimate with them so recently makes me feel extremely uncomfortable when he spends time with them. (When I say them, there are only two. it's not a multitude of hookups). I have broached the subject a little, but he feels that since he has no emotional attachment to them, it's not something that should bother me. But it does. Any thoughts on how to let him know what I'm feeling without sounding demanding or possessive? I do not want to be the girl that tells him who he can or can not spend time with.

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<bot>: my boyfriend talks to/spends time with exes/hookups and it makes me uncomfortable. How do I express that without sounding 'overly attached'?