Thoughts about cheating

So I was going through my boyfriends phone just for fun and I saw a message of him texting his Friend and it said that when he doesn’t get to see me for a long time sometimes he feels like hooking up with someone real quick but he won’t because it’s bad. I don’t know how to feel about this, should I end our relationship? We tried talking it out and he apologizes and says he doesn’t deserve me and all that crap. I need advice !