After a two-year relationship came to an end, "Glamour" editor Ruhama Wolle jumped back into the dating pool—only to find it was a puddle.

“The minute they went on live shows he didn’t message me back, and I thought ‘That’s it now. He’s gone, he’s made it,’” Thirlwall said. “Then I made it [as a member of Little Mix] the next year and ...