Need advice

Me and my fiance have been together for 3yrs. But here lately he has become very distant from me and I'm not sure why. He doesn't want to do anything sexual or even spend time with me. He leaves early in the mornings and doesn't come home until 10pm or later. There has been nights where he won't come home until 1am. He has completely pushed me to the side. He was gone all day on valentines. He came home long enough to leave flowers and a card then disappeared again until very late. Does anyone have any advice on how I can make things better between us. I'm willing to try anything. Please