Your H said he would come up with desert. Have no expectations one way or the other that he will or will not.
If he does, great. If he doesn't that's OK. No need to prod him about it before the fact. And no need to judge him after the fact, if he does not produce or if he does not produce to your expectations.
Would the event fail completely if he forgot desert? If there was no desert? Is this an issue about whether he can keep his promise or not and if he does not provide desert, it just further proves that he either lied or just too self absorbed to care about anyone else?
