Need advice on 3.5 year relationship

I am 46 y/o with an 18 y/o and a 15 y/o boys. I have dating the same guy for 3.5 years and we live an hour apart. We only get to see each other a couple times a month. We do love each other but we seem no closer to making our lives seem like we are a couple. I want to move in with him but that means letting my 15 y/o live with his dad so he doesn't have to leave the school district (my son's choice not to move out of the area). Dad is not going to win any Dad of the Year awards and I really don't want to make my son live with him, but I have put my life on hold for 5 years for the sake of my sons. My relationship goes from great to very rocky. My boyfriend is 50 and has been single for 10 years since his wife passed away. At times I swear he is seeing someone else but he swears he isn't. I guess that distance between us and the face that I don't know what he is doing most of the time leads me to be not so trusting. I work 2 jobs which means I work a 14 hour day 4 days aweek and 8 hours 1 day. I don't want to hurt my youngest (the oldest is off to college next month) but I want to be loved again on a daily basis. Any suggestions??