my bf and i have been together for 15 months, we only started having sex 6 months into the realtionship. we plan on getting married and are crazy about eachother. however, everytime we have tryed to have sex, the total of 4 times, he can't orgasm. he can get it up just fine but after awhile he gives up because it won't go. because it has failed so many times he has pretty muched given up on us having sex. what should i do?