The evidence clearly shows that Melissa forgives Craig bro. This one I struggle with, so Melissa must have assumed that Craig and Kelly were murderers because Craig was a wild boy - HHHmmmm I wouldnt want to give that explanation to Melissas Mother
Firstly, she knew his nature and she stole from him. This is like cutting off your finger, sticking it in shark infested waters, and complaining when your hand gets bitten.
Secondly, she loved Craig and was deeply sexually attracted to him. She would want him to be happy and sexually active , with females.
Thirdly, she knows that the candle that burns twice as bright, burns half as long. She had her special times with Craig and knew he was a livewire. She understands how this shit happened and accepts her part of the blame.
The best way I can elucidate things is this: Richard Dreyfuss was attacked by Jaws and the damn thing ripped up his cage trying to get at him. However, in Jaws2 when Chief Brody calls him up for help, where is he? He's out in the Pacific tracking and monitoring great whites. The point is that he understands it's in their nature to behave in such a way. He forgave Jaws.