Thanks for writing to JA.
You may be experiencing the ebb-and-flow of many committed relationships. In fact, struggles around years 5-10 in committed heterosexual relationships are so common, a classic American movie was made about it. Ever hear of "The Seven Year Itch?"
I would strongly recommend that you consider couples counseling... which you would initiate on your own (individually) first. Meet with a couples counselor to discuss your feelings, misgivings, hopes, goals. If you can clarify what you want and hope for in your relationship, then possibly couples counseling could proceed from there (with your partner). Some couples counselors may suggest that they will only work with couples as a unit - or will not see individual clients - in which case you may have to seek several professionals. Should you decide to move into couples counseling with your partner, s/he may also want to have a counselor who sees you as a couple, rather than as someone who saw you first and is now seeing both of you.
The goal of couples counseling would be to increase effective communication between you and to bring you closer together toward common life goals as a couple. The reason I suggested you consider individual counseling first is because your post suggests that you might not be certain that you actually want couples counseling. Best to explore that a bit on your own first.
Not all licensed mental health professionals specialize in working with couples. Some work with individuals, couples, families, and groups. Be sure to ask before you "take the plunge." If $$ is a considerable issue, look into your local (town, city, county) Community Mental Health Center/Service. They often offer therapeutic services at a reduced cost.
I do wish you the best of luck with your issue(s) and hope that this feedback was helpful.