I have to jump in again on two things: Nobody outside the conservative religious community still considers homosexuality a choice--and I've had friends very unhappy that they were. I suppose the practice of it is a choice, but how many of us seriously advocate lifelong celibacy? Even in institutions which sanctify it, it doesn't appear to work too well, as witness the priests'scandals. Also, please show me where in the Bible it is condemned; the "spilling seed upon the ground" regards onanism.
Second, as I've also said before, the meaning of marriage is defined by the two people who make it--often as they go along. For myself, I'd agree that the ideal is lifelong, loving commitment; I've also failed (with help) at that commitment. Many people enter marriage conditionally, for as long as it feels good. Some enter it for financial or other practical considerations such as citizenship; while I don't personally agree with either, the law recognizes them equally--though when it can be proved, the citizenship dodge is an exception.
I could make the same arguement about sex--for many it manifests a deeply meaningful connection, for some it's good, clean fun, for others it's as meaningful (or meaningless) as a handshake; it also has its practical and financial aspects. Ditto friendship; few things are more meaningful to my life; for others it's a social expedient and/or offers financial/material advantage, and can also be a life-long commitment or a passing notion. The point is that none of us can or should define it for others. I agree that the legal protections desirable for society can be met separately from the institutions, and often already exist in the civil code.
BTW, isn't it amazing that what started as a nitwit flaming thread has morphed into several substantial topics?!