Relationship crisis

I’m just scared of falling for someone else that is not my current boyfriend. I don’t have feelings for anyone else but I’m scared that in the near fritura, I am scared of having those feelings. I’ve always been someone who overthinks, and lives sometimes just in the future, so maybe this is just another pointless thought I’m having. I guess I’m not 100% confident in my relationship because I’m not confident in myself. I just need help, can anyone help me to be more confident in my relationship? I want this love I have forever, but I’m just scared I’ll fall in love with someone else. Please don’t give me hate, I just don’t know what to do. I’ve talked to my bf my thoughts are sometimes still there, also I’ve read that some people in long term relationships have small crushes on others but really it goes away fast. I don’t know if this is true? but please give me advice, I don’t want to break up with my boyfriend. Also it maybe the distance that we’re in because he’s in the military that is creating these thoughts. Please help, thanks!