It is true that Callum is happier with molly, he wasn't affectionate to Shauna and did appear frustrated at times, and there was no affection, they weren't snogging in bed, all touchy feely
As said, I can't understand how she translated it to mean she should quit her job and move to Manchester to be with him, it's like his feelings didn't count. Yes he was with her, but he was hardly doing a mike and proclaiming his undying love.