You need answers. So here they are.
Men disappearing without an explanation (AKA, ghosting) is a huge component of a single girl's dating life, so let's address it! In my experience, I find that if a man disappears for good, it's because of one of two reasons.
1. He did something wrong or hurtful.
I've never met a man who liked facing me and admitting wrongdoing. Neither have my friends.
I once explained it to a girl like this: A lot of men are all about pride and dignity. Women are too, but we know we can't survive that way. We might need to approach a stranger and ask her for a tampon. Men can't or won't do that. They would run across the street and buy the tampon themselves. But women are willing to show a little vulnerability, admit we're empty-handed, apologize, and ask for help.
2. He suddenly realized he was headed toward a relationship.
Girls plan ahead. What will I wear on this date? Will I go to second base? What should I say if he tries something? Should I shave my legs just in case? Will he ask me for a second date and should I say yes? Will I end up marrying him?
Guys don't think ahead. He might have said something about the future ("Let's go to Santa Barbara one weekend"), but it really says how he was feeling in that moment —happy, road-trippy — and not about wanting you in his life for a future weekender. (I know, false advertising! And such a strange way to express your feelings!)
At some point, maybe even six months into dating you, he realizes he's committing himself, and he takes the easy way out — he disappears. He knows this is a bad thing. You should know he knows — and that will have to be enough, because you probably won't convince him to come back. He's not ready for the responsibility of a relationship.
What he knows (rather conveniently and optimistically) is that you'll be fine because a worthier man will snatch you up soon enough. Possibly a man who could ask for a tampon — on your behalf, if you were stranded, and in a complete bind.
Of course, I'm only speaking from my own experience, and the patterns of behavior I've observed. And this is the only way I can explain it to other women.