Is it me?

Ok so me and my SO has been on and off for 8 years now we just got back together about 8 months ago and live together in our own place now he's a police officer and I start college Tuesday the last 4 times we had sex he didn't finish tonight after he got "tired" he says I have to go use the restroom so me being curious I waited till he was out and went to pee and there's cum on the very edge of the toilet seat I mean is it me am I not enough when I got out I went to put my cloths on and asked him about not finishing he said he felt like he was in the mood but he guessed not I asked him if he did "finish" he lied and said no someone please help me I don't take him as a cheating type but he was a player years ago I love this guy and plan on spending my life with him