Details: Quinn and David were happily married for some time but, as
Quinn would later state they stopped doing the little things for eachother and everything became too routine for Quinn. This caused her to leave David and return to Tree Hill to spend time with Haley and her family, while trying to avoid David at the same time by dodging his calls. David eventually arrived wanting to speak to his wife but their talk resulted in Quinn asking for a divorce. That night Quinn made the choice to go back to Clayton's house to get David to give up hope and, despite the fact they talked all night, David did give up hope and said his final goodbye to Quinn before letting go of her for good. After the divorce they left in good terms and still friends.
Details: After he divorced Quinn due to them changing and falling out of love, Taylor and David returns to Tree Hill and moves in the Scott household with his new girlfriend, Taylor. David and Taylor flaunted their relationship in front of Quinn and the Scott family, resulting in a fight after Haley tried to make Taylor see that what she was doing was wrong. However, Quinn later gave Taylor and David her blessing on the condition that Taylor wouldn't hurt David. He eventually left Taylor, however, after realizing their being together wasn't right. The reason why he broke up with her, because he was afraid to get hurt again, with Taylor track record with guys. He can't risk getting hurt again. Even though Taylor was really in love with him.