Personality and open relationship

My boyfriend and I have been together for 5 years. We've been sharing a home for 2 years and we're in an open relationship. But there's a question bothering me: do I have to tell him everything I do (sexual or not)? I have some doubts. We're both 27 years old.

And because of our open relationship, we have less sex with each other. Is this a problem for other gay people?