Husband can't keep an erection lately

So we have been married for a year. sec was like everyday sometimes 2-3 times a day. Recently it doesn't matter if its early morning, late at night. when we decide to get it on his dick just won't stay hard. Is it me or do you guys think he may be cheating. I'm stumped I dont know what to think, and it's always his idea to start so if he wants it so bad why cant he keep it up. He will text me during the day with sexy talk and describing what hes going to do to me when he gets home then we start kissing and touching when he gets home. then as soon as he starts to put it in it deflates. I want to say something but I dont know what to say. Should I be concerned that hes getting what he needs from someplace else.