Alex was married to Chelsea Melini when they were young. They remained married for eight years before they divorced. Chelsea remained close friends with his mother even after their marriage broke apart.
His mother dies before the events of "She'll Still Be Dead at Halftime" and Chelsea decides to attend her funeral in Santa Barbara. Everyone attending the funeral including Chelsea at his parents' house until it is over.
At the funeral however, Alex tries to put the moves on her and she decides to leave.
In "Captain Terry's Spray-On Hair", Chelsea states that he is going to marry another woman and she feels frustrated because he's over her.