I know im unhappy.

Me and my boyfriend have been together for a year and a half. I really love him, and he is my best friend. Recently (about 5 months ago) he got a new job, his confidence has soared and he is really enjoying it, which is great. He has changed, a lot, though. I've tried to talk to him about it, but he gets very defensive. He seems less patient with me, and less affectionate. He still is, but it just feels like the oomf he had towards me once has kinda gone. The thing is, I know im unhappy. I feel like its because of this job, but I would never/could never ask him to leave, he's so brilliant at it. I think it's just the environment he is in now. I cant bring myself to tell him that I'm unhappy now since our relationship has changed a lot, I dont know if it is going to change or if I'm just in a lul and focusing too much on this. It would break his heart if I told him I'm unhappy and I think that it would be the end of the line, rather than something we spoke about and tried to fix. He's the love of my life, I'm just not sure he's the same person anymore and I don't want to change him. I'm sitting on my bathroom floor in tears as I write this. I dont know what to do.