To properly train your Sissy that he must put you above all his needs, you must immediately limit his orgasms!!!
Once he understands that cumming is a privilege that you can grant or deny as you wish you can begin offering orgasms as rewards for good behavior!
Soon any request to cum must be accompanied by a promise to lick it all up and the creative wife will soon learn that where he licks it from can add that extra level of humiliation that Sissy needs!!!