Anxiety disorder treatment for bf

Hey, my boyfriend becomes very tensed when we get intimate and this is irritating me like anything. Once we tried to have sex and his anxiety ruined the moment. I am in a doubt whether to marry him or not. If he cannot handle such silly tasks, I am doubtful about the way he is going to manage big challenges in life. When I discussed this matter with him, he told that he is going to undergo an anxiety disorders treatment from Toronto. Is this treatment effective in solving this problem? Please give some genuine replies and suggestions. Thanks in advance.