Sam/Callen story. D/S (You have been warned.) Callen needed to learn how to accept love, to learn that he wasn't alone. But how did he do that? How did Sam get past his defenses to help his friend.
So his sweet girlfriend did as those who weren't stars always did. She bandaged up her heart as best as possible, offered a wry smile, and gave him up.
Because he didn't love the girlfriend. He loved the new girl.
And the new girl had the makings of a star.
And stars, it seems, always get the happy ending.