Personally, I don't think Owen fell for Gwen, he simply used her as a convenient shag for when he couldn't be bothered to go on the pull. It seemed to me that her going on about her wonderful boyfriend annoyed him. She was happy while he'd lost his love, so he set about seducing her to prove he could. After all, if Gwen had loved Rhys as much as she claimed to, he would have failed. He proved a point and showed Gwen up for what she really was.

At least this gave him something to be happy about!

Thank you!