Couples Counseling is similar to marriage counseling but with some differences. Couples Counseling is more of guidance and discovery about yourself and your partner. It does matter if you are heterosexual or not because all the same human behaviors apply.
The typical problems couples have are slightly different than that of married couples. There are fewer legal bonds and different expectations of the relationship.
Other typical problems are learning curves about each other are much steeper when compared to a married couple as the relationship tends to be younger. There can be culture clashes and third party influence are much higher in younger relationships.
Couples Counseling looks to repair damage cause by clashes and to reduce misunderstandings without placing the blame on anyone because most mistakes are accidental and not malicious. Because of that cultural education is often a part of Couples Counseling as increasingly couples come from a different upbringing. So in many ways Couples Counseling is like going to school to learn where not to step and to find that midpoint that is acceptable to all.