I am so relieved that Ashley is free of David. Yes, she was cold to him. But it was all his doing. Just because he wasn't as frenetic as Sam didn't make him any less of a creeper.
The trouble with David is that he's two extremes. On one side, he claims he's desperately in love with Ashley, but on the other, whenever she does something that upsets him, he freaks out and gets really angry. Remember in season 1 when Jamie wasn't into Doug? She told him, and he dealt with it, and they both moved on. But when Ashley tried to admit the same, David suddenly got really angry at her. Ashley was so guarded around David because any disagreement on her part would only provoke David into being emotionally manipulative, and try to make her feel bad with his aggressiveness.
David never knew when to calm down and chill. He was always pressuring Ashley, and he couldn't just relax and try to let things take their course. And when she admitted that she wants a divorce, he acted like a child -- constantly showing her pictures of them together and asking if she wanted them, and throwing a hissy fit on his way out the door.
A telling thing was when, several weeks in, David claimed he loved Ashley. Mind you, this was after weeks of cold fish, establishing that either David was lying, or simply naive. Honestly, David so strongly desired marriage that he became desperate and over-aggressive. It didn't matter to him who he was married to, so long as he was married.
Both David and Sam are too childish to be married.