Would a very attractive guy date an average girl for two years if he didn’t love her?

Yes, he'd probably be cheating on her. Honestly she sensed it for 6+ months too. But she was too scared/concerned to do anything. She probably blames her self too.. There are lots of reasons he would but you gave us no details.

Of course he loves her or he wouldn't waste time. Not to mention looks aren't what keeps a guy there. Looks fade and beauty is in the eye of the beholder. While I know my boyfriend finds me attractive I believe what he likes most about me is my transparency and that I am always there for him no matter what.

maybe he hasnt met girl more charming .

For the sex? for money? for popularity? How should I know.