Why is it that people want you when you are in a relationship?

[ThePriceIsWrong]

Ok i know this sounds dumb, and i thought it did too. But the whole thing where people complain about when they're single nobody wants them, but when they're in a relationship, people are interested in them. I thought it was bs until it happened to me. The week after i got in a relationship, one of the hottest girls in my school who im friends with asked if i wanted to "Hang at her house before her parents get home so we can have fun" and all these girls on twitter DM me trying to say hi and stuff. Obviously i declined and dont message back, but is there a scientific explanation for this or something? It seems kind of far fetched and crazy but i thinks it's true. Any reasons?

[Markesse]

People want what they can't have

[Alex]

It's so strange. People are interested in what is so special about you for them to date you. I really don't understand how it works for individuals, but I can see how it works for toys, games, accessories, etc.