Is my boyfriend cheating?

Bella

So my boyfriend always has his moments, lasting for days, where he acts like I don’t even exist and won’t talk to me. If he does talk to me during his moments, he’s very rude and tells me I piss him off or I’m dumb and stupid. But when he’s not having a “moment” he’s everything I could have dreamed of. Tonight some girl was on his Snapchat sending his streaks after he abruptly hung up the phone on me. I have had some suspicion before about him cheating on me but he always denies it with full force and won’t let me think that way. I have no idea what to do, I’m at a dead end here. I really don’t want to break up with him, I love him so much and he’s been here for me as I’m going through a huge family situation. Please help 😭