Is it me or him?

I been with the same guy since I was 17 I’m now 23. We’ve lived together for the last 3 years & everytime we have an argument he runs to his moms house & makes facebooks & hits a bunch of girls up.. is this because he truly doesn’t love me or does he do this because he can’t be alone?! Like I just don’t freaking get it!! He says it’s because he’s “bored” but isn’t bored enough to fix our issues without running to his moms like a little girl... it’s crazy bc I’ve noticed his mom does the same thing. She’s never single for long before having another dude in her house. Like a week or two she’ll be in another relationship.. does he not love me? Or is this a problem within?