Your right, when the attraction goes it's certainly hard to sustain a relationship no matter how hard you try.
Honestly the people who say looks dont matter really talk nonsense. I mean the reason you want to be with someone is due to an attraction and the attraction is based on looks and personality, not purely on one or the other.
OP in terms of your situation it's difficult but that is a MASSIVE difference and if you just arent feeling it now then thats understandable.