I don't get it!
I would say just cut your losses. Trust is the hallmark of any healthy relationship. If you don't have trust, you have nothing. He is already lyimg to and cheating on you. I can't imagine why you would not confront him. Why are you so ready to hang on to this guy? Moving in together would be the last thing on my mind if someone had been lying to me.
End the relationship. Really, this decision should be a no-brainer. I understand the desire to post and ask people for advice because you want to feel more strongly about your decision with the input and validation from others. However, you really should know in your heart that you don't have a good relationship and you can't have a good relationship with a liar and a cheat (and yes, of course he cheated on you).
It always amazes me to see people in relationships as short as yours settling for someone who doesn't feel very strongly for them. If his interest has waned after only two years, what are things going to be like in twenty? Hopefully you won't stick around to find out, so that in twenty years you can have someone who adores you just as much as the day he met you.