Haven’t had sex in almost 3 months.

My fiancé and I haven’t had sex in almost 3 months. Is this normal? He says he just doesn’t have the urge. Which is hard to believe because he used to watch porn on his phone all the time. Now I haven’t seen porn on his phone in a very long time.. but it doesn’t mean he isn’t looking at it again. I’m starting to become very insecure because I feel like it’s my fault he doesn’t want to have sex. I’ve gained about 20 pounds since starting my new job so maybe he thinks I’m unattractive now. I have all the negative thoughts going in my head the longer it goes without sex. I honestly feel like there is someone or something else that’s grabbing his attention. What’s do I do?