Credit: Jae Donnelly/ (2)

Their marriage lasted a mere six months, but Corey Simms will always think fondly of his ex-wife, Teen Mom 2 star Leah Messer.

"Corey still has feelings for Leah," a source close to Simms tells Us Weekly. "She is the only girl he ever really loved."

By late 2011, Messer had clearly moved on, accepting an engagement ring from Jeremy Calvert. "Corey is trying to move forward with his life, just as Leah has done," the source explains. "He is trying hard to get over her."

Messer, 19, and Simms, 21, have always had a rocky relationship. The two dated for one month, found out they were expecting, split up after the 2009 birth of their twins Aliannah and Aleeah, then reunited six months later. After moving in together, Simms proposed. They tied the knot on October 17, 2010; Messer filed for divorce the following April.

"Corey wishes his marriage would have worked out but he knows it's over. He knows in his heart he did all he could do to make it work," the Simms source tells Us. "He is staying busy working on his new house trying to get it ready for his girls."