It's no secret men and women communicate their thoughts in drastically different ways. Women give hints. Men "ignores" them.
Don't waste your time giving subtle hints that he won't understand: Be direct. Be honest about your feelings, and don't bottle things up until you everything comes snowballing down on your marriage.
If he asks you what's wrong, don't respond with "nothing" or "I'm fine" and then expect him to read your mind and emotions. Be open about how you really feel.