My homosexual cousin wishes to ‘marry’ is longtime boyfriend.
A very small part of me wishes them happiness.
However, whenever I read his face book rantings regarding Religion especially Christianity, I see a seriously confused young man whose extreme hatred of all that is Religious just might be a cry for help and a thin disguise for self hatred regarding his chosen sexuality.
I think you desire to wish your cousin happiness is well placed.
However, as you probably already realize, a homosexual relationship will not bring him happiness.