Just let things be now...he said he has no thoughts of leaving you, loves you, and wants to buy you the house to prove it...
I think you will be okay...he needs to revisit for closure...maybe the bet was she wouldn't move away or some other silly thing...but either way you can't control him...if they have dinner and he comes home and she goes away...well then you have made it to the peak of the hill again...and maybe this is the last down hill part of the rollercoaster ride until the end...
Hold tight...you made your little inquiry...you did good not hounding him on it...I have a feeling he answers you more then you realize and you don't understand...maybe that is something you could focus on better...understanding his methods of communication?
