So this thread seems to have morphed into a sort of discussion on the merits of marriage.
Personally, while I understand some of those who have no interest in marriage, I feel that it's an important institution not because of the inherent heteronormativity- but because of the deeper symbolism. It's a significant celebration of commitment between two people. It's powerful because of what it represents, as well as all the benefits that society has heaped on it as part of supporting that level of commitment.
Sure you could quietly stay together as a couple without ever getting married- but for others it matters because it helps them proudly have their commitment recognized by their community and by the legal institutions which can protect their commitment to each other.
Back on topic- living in a country with a strong Catholic presence that meddles in all aspects of life- it isn't likely to be legalized here anytime soon. But the recent level of acceptance in other countries is encouraging. I'm confident someday it will be possible.