I think it is a sub's job in this instance to do some proper service orientated BDSM. Simply be there for him if he needs you, cook his meals, make sure the house is clean, make his life in the vanilla world as easy as possible. Offer to do things for him like give him a massage, rub his feet or perform oral sex.

These activities have two main effects. First you are engaging in a sub role and so should be getting some of that nice feeling you get from doing sub things and these don't even require him to particularly participate in the process other than to be there to recieve the attention. So he does not get more stressed because he has to think about BDSM and plan stuff. Secondly, if he gets relaxed enough he may feel more like playing later. The better you make him feel, the more likely he is to want to play.