I agree with whoever said we were supposed to like both of the men and empathize with MElanie and her decision making process.
I also think it was easy for Andrew to let her go because he knew that in her heart while she loved him, her heart forever belonged with Jake. Plus if he really wanted her he would have tried to convince her. Andrew could give her the material but Jake could give her the familiarity and he loved her for her: the good, the bad, Smooter, the dead dog, Felony Melanie
, etc.
Oh and they did a brief talk about the miscarriage at the Dog Cemetery.
Ultimately Melanie being away for all those years taught her some things and caused her to mature. Even though she "rejected" a lot of her past, that past was still there to accept her, success and all.