It's because you're over that 'romantic and passionate' face of your relationship. It usually lasts 3-5 years and then it becomes affectionate love. It's normal.

Why don't you two try to do stuff that you did when you fell in love? If you like him, the best thing is to start all over again. Reset a bit your relationship. Change your habits. Try what you can before end up things if it's a good relationship.