You don't mention how old you are, but I think our situations may be comparable to an extent. I'm 24 and have been with my boyfriend for 4 years. The difference is that we live together. And have been from nearly day one. If we were to get married, there really wouldn't be many, if any, changes in our relationship.
And that's how I expect a mature (and 5 years with a partner ought to be a mature relationship!) relationship to be.
Do you live close enough together to see each other most nights? If yes, then he needs to learn to commit more to this relationship; make him know how important he is to you.
Have you communicated how unhappy you are? I'd feel terrible if every time I saw my bf it would involve sex. This is definitely not the only way to express your love.
If you want to see more of him, make it known. Ask him how ready he is to commit to you. And let him know that marriage is not supposed to be a huge catalyst for change. He can live a "married" type of life with you right now just as well.