So me and my boyf have been together for almost a year. We both have friends of the other gender and are completely comfortable with that etc etc etc 

The other day when he was at my place, he was on whatsapp and I saw that he had a convo in it with a girls name that i’ve never seen or heard before. The only thing I could see is that a “heart” emoji or something like that was sent. 

I didn’t say anything about it but i’ve been noticing that it still hasn’t left my mind and it has been giving me a lot of anxiety. 

I really wanted to ask him about it. Just like oh hey the other day i saw this and sometimes I overthink a bit so I just wanted to ask you about it etc etc. 
But I am so scared that it is going to come across as controlling or that I don’t trust him or anything in that sense. It’s not that I don’t trust him it’s just that these things sometimes give me a bit of anxiety and I always kind of need to make sure. I know it’s not a good trait I have and it’s going a lot better than before but I can’t seem to let it go. I’ve been having dreams about it and a lot of anxious thoughts. 

Should I just try to deal with it on my own or is it okay to ask him? and how should I ask him if so. I’m just so scared that i’m going to seem controlling or needy or anything in that sense….. I just want to calm my own mind that’s all :( I wish I wasn’t like this