Within the context of discrimination, one of the most used "weapons" of those against equality is the notion that people "choose" to have a homosexual orientation. It is important to challenge this myth, because it forms a key part of opposition to equal rights for gay and lesbian people.
A celebration of the love of two people should always be permitted and will always be desired. No one is suggesting the suppression of that aspect of marriage. But legal recognition by the state should be exclusively under a different set of "Plus One" laws.
Even without a causal link established between homosexuality and population management, the obvious reduction in population growth attributable to homosexuality by itself indubitably works to preserve the species.