yes, our hearts broke a little bit too when we heard...

Ashlee Simpson is set to marry Fall Out Boy star Pete Wentz -- after the pair got engaged earlier this week.

The loved up couple were on a trip to Colorado--where Pete's brother was exhibiting artwork--when the bassist, 28, asked Ash, his girlfriend of almost two years, to marry him.

A friend of the couple tells In Touch magazine, "He got down on one knee and she said yes. She has an amazing ring, and they are so in love."

In a statement released shortly after news of the engagement broke, 23-year-old Ashlee admitted, "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. Thank you for all of your support and well wishes--it means the world to us. We consider this to be a very private matter, and we wanted to be the first to tell you and to hear it straight from us."

Noooooo!