Is he cheating?

abbie • Been with my man for over a year and couldn`t be happier :)
He will always be late to my house and never have an excuse. I went through his phone and didn't see anything but he could've erased them. Idk if I'm just being pariniod. He acts really different. His temper is very short and he's been really mean. We both had the day off today and he's just now coming when he had all day to come it's 7 pm right now and he's still not here. Idk what to think. Please help