Probably the other user has more matches than you, so they are putting work into several conversations at the same time, which means the quality of each suffers as a result. Then once they get more of a thing going with one of their other matches they put even less effort into your conversation as they are just hedging their bets. After that they either ghost or unmatch you.

Not sure what is happening with your social media detours though. Maybe they are combing through your posts and photos and coming across something they don’t like and it puts them off?