Saying this again, his suggestion sounds like, "I can't marry you but I can give you the most superficial illusion of a marriage". I find it really inconsiderate. Sure you can not want marriage but I dislike the attitude.
Anyways I don't believe in a relationship where one wants to get married and the other doesn't. nyari masalah namanya. Better end it before getting hurt any further.
Adding whatever is obviously not following the recipe....