Ashlee Simpson and Pete Wentz engaged

Ashlee Simpson is engaged to Fall Out Boy rocker Pete Wentz, Simpson's rep has confirmed.

"Yes, they are happily engaged," said the rep.

Ashlee, 23, said of the engagement, "I'm really happy!"

Rumors are swirling that the pair are tying the knot because Ashlee is pregnant, her rep, however, had no comment and referred us to friendsorenemies.com, where Simpson posted the following Wednesday:

"We know there has been a lot of speculation recently about Pete and I, and we wanted our fans to be the first to know, because you guys are the best. Yes, we are thrilled to share that we are happily engaged."

Simpson and Wentz, 28, started dating in late 2006.

"They are ecstatic and can't wait to be man and wife," a source said. "They will be getting married before the end of the year."

Wentz said earlier this month that he was open to marriage.

"When you find someone you think is your soulmate, it's inevitable," he said.