Fear of wasting time :/

I'm not sure if it's past experiences, but I am constantly thinking my so is cheating on me. It's odd he takes his phone in bathroom just about ever time he goes in there... and insists he's playing his games. I almost have to beg for sex he says it's not like that but that's not how he makes me feel. He seems bored with me , should I just leave or am I doubtful with him ?