Why do guys ghost?

I’ve been talking to this guy for about a month, and legit talking, like we had conversations just about everything on a daily basis, we were each others #1 on snap, and he would always tell me things like “you’re so beautiful oh my god”. He was just different than any other guy who had ever talked to me before and he genuinely respected me. Then one day out of no where he took the whole day to respond, when he responded it was like normal but then over the next week he just kept taking longer and I had got the feeling he was either pulling away or losing interest, but he was SO into me I felt like there’s no way he’d lose interest that quick. He finally hit me up again and we were snapping then all of a sudden he was calling me beautiful again, & then outta nowhere he sent me a dick pick and then left my fucking response on delivered for six days now. I know a lot of y’all are gonna be like fuck him, who cares but I just wanna know why he did it, it bothers me so much and I pretend not to care but I do.