I'll discuss.
I personally care little for the institution of marriage, which to me seems somewhat outdated. I don't oppose it, but nor do I actively support it.
For me, I'm not an expert on US law, but the problem in the UK, which may also be copied in the USA, is the inability of people do seperate the contractual, legal aspects of marriage, and the status of marriage as a religious ritual.
The solution seems clear:
1. Let people engage in whatever religious rituals they wish (providing those rituals do not harm others or violate other relevant laws). But do not grant those religious rituals any legal status whatsoever.
2. Seperately to (1) above, let individual adults enter into contracts with each other, which may or may not be called "marriages" and be founded on the same promises and exchanges as underpin a traditional marriage. Naturally this right would be extended to allow two adults of the same sex to form such a contract.
3. If people wish to arrange an event, religious or non-religious, to celebrate the signing of the contract provided for in (2) above, let them do so. If people wish to arrange such an event to co-incide with, or be part of a religious ceremony as described in (1) above, let them do so - as long as it is clear that (1) has no legal status and (2) is a seperate legal process.
Problems = solved.