My husband and I don't have sex

Well, the title says it all....my husband and I don't have sex. We've been married for 4 years and together 6.5 and we have only had sex once, which is when we were going to marriage counseling to work on this issue. We've talked about it, argued about it, and I've cried about it....but no change. I have no idea what to do. I love my husband and we have the best marriage in every other way. Suggestions????