Guess we now know whose love is a drug for Ke$ha.

The singer, who has been ambivalent about her sexuality in the past, has gotten serious with drummer Alex Carapetis. He accompanied her to Chicago this weekend for Lollapalooza, where the duo got especially cozy at the Music Lounge together.

"They wouldn't stop making out!" a witness told E! News. "They have natural chemistry and are always laughing."

Sources say Carapetis, who is Australian, is considering a move to Los Angeles to be closer to the eccentric singer. And why not? If their taste in sunglasses is any indication, these two have a lot in common. We wish them the best!