Why is he like this ?

I first met my fiance on 10th May this year and he couldn’t keep his hands off me but now its like he has changed he is not all over me like he was anymore why is he like this now and he only makes luv to me when he feels like it yet he still says he loves me very much and that im the best hes ever had and he still wants to marry me sometime next May, i love him too very much but how do i get to understand him properly