You know your friend doesn't like cake very much. But you have a great recipe with special ingredients that are good for his health (in addition to the fact that it tastes great). So you make him the cake, and he is free to taste it or not, without any obligation.
Based on your example, you're already know the answer! You shouldn't be sad or mad when your friend doesn't want to taste your cake, as he was not ask you to make him a cake.
If you're still seek a way or trick to make him taste your cake, you're not respect his decision. You can't generalize anything is same, if you think it's good for you, other people can think it's not good for them.