In trouble

Okay ladies I need your help! My partner and I have been together 3 years, up until mid last year things were perfect and then I'd read some inappropriate messages between him and another girl which we talked out and I'd forgiven him and things were good. But recently the past 6 months he's had these insecurities about me cheating on him, that I'm not sexually attracted to him anymore ect. I've done everything in my power to make him aware that I'm not cheating on him I would never do that since I know what damage it can do to people and my personal experiences from it. We use to have sex multiple times each day and now we are lucky to once a week but it's not because I'm not aroused by him or that I'm cheating on him, I don't find myself sexy which struggles to make me aroused, I think my partner is the sexiest person I've ever met and I love him with everything that I've got but I don't feels sexy which I think is what's holding me back in the bedroom. I don't know how to make my partners insecurities go away Or even improve them and it's getting to the stage where I feel that whatever I do makes him angry or upset, I just feel like I can't do anything right.