Why can’t I let go of stuff of what my fiancé does?

We have been together for a while he’s never cheated in any way or form or done anything drastically but like I’m pregnant and I asked him to get me something wasn’t feeling good and he was like I’m on the game 10 min then it was 20 and whatever I keep thinking about it but I don’t know how to let it go I feel it was more serious then it actually was you know? Like I know it wasn’t that serious but if I was in pain and needed some he could of left the game for about 20 sec just stuff like that I’m not sure how to forget or let go of and I think of it for a while