Jealousy

Okay, I already know there's going to be that one bitch who comments on how insecure I am, but honestly. Am I crazy for getting jealous when my boyfriend texts other girls? Either from work or just anywhere. Girls I don't even know. I never look at his phone because honestly I don't want to start anything but I have seen on his Facebook where he's had causal friendly conversations with girls over messenger and then gives them his phone number. We have been together for three years now and it just really bothers me. When I text him he's always been a kinda boring texter. But over messenger he seems to give more effort into talking to everyone else. But the messages aren't flirty. At least not that it seems to me. Idk this just really bothers me and if I bring it up to him he'll get all mad because he'll claim I don't "trust him" 😭😭