Ladies, why do you just leave guys high and dry?

I'm a (24y/o) man. See my self as pretty respectable, cool person to be around, and not bad looking at all. But I met this girl who I thought was pretty cool too and we seemed to hit it off pretty well. We've hung out a few times for a few hours. Even started to make out and cuddle up. But now she's straight up not messaging me back or anything now. It's not like this is the first time this happened either, it happens with almost every girl and it's getting to feel like I'm just a plaything that can get tossed and easily replaced.