According to Matthew [The Gospel of Love 2]

Unlike his older brother, Matthew Finley has no problems with commitment. A creature of habit, he craves the predictability of marriage and family. Unfortunately, his most enduring habit is his commitment-shy ex-girlfriend, Casey Franklin. After five months of going cold turkey, Matthew comes home to find Casey waiting for him, and he falls off the wagon. Hard. But he still wants forever, and she's still not ready to look beyond tomorrow, leaving him two choices--overcome his addiction or her resistance. And that's really no choice at all.