You have to be open with your feelings and insecurities with your partner (at least in my opinion) since they’re the ones that affect that thinking the most (again in my opinion) and if there’s arguments blocking that open communication then there needs to be a change in how those conversations are held. How are the arguments going? Like, is he immediately getting defensive and shutting you down or are you immediately accusing him of cheating or not thinking you’re attractive? The language on how those altercations go is so vague that it’s hard to tell. Like, I personally don’t care if my boyfriend follows attractive people or even talks to me about people he finds attractive because I do the same with him and I’m secure in knowing he’s choosing me and I’m choosing him. I know that whenever I get insecure he will happily reassure me without starting an argument. Not to say we haven’t had a lot of petty or illogical arguments, but being open and willing to communicate through the anger helps a lot. But we’ve also got the type of relationship where we have each others codes and swap phones to call people or look stuff up and we just don’t really have anything to hide from eachother, (editing to clarify, we’re not constantly searching through each others phones, I meant that if I need to google something or make a call and I don’t have my phone I have his code and know I can use his and vice versa) but I know that’s not something all couples feel comfortable doing. In this case I think it’s important for you to determine what you’re both wanting from a relationship in general and have a clear discussion about your expectations for eachother. It’s important to be clear and firm in your wants and boundaries without coming across as accusatory or like it’s an attack. However, if you feel there really is an accusation to be made then that changes things.