I always have a negative reaction when a friend tells me s/he's getting married. It just seems so dull, so old-world and unnecessary. Marriage is tired.
If you and another person are in love, you should stay together. When and if the love dies, you should part. I don't see how making a financial bet (marriage) changes this, except to make it more painful and labor-intensive to break up.
It's just creepy. And for gay people, marriage seems unutterably dull. Now, adding kids to the mix muddies the water. I understand: you think marriage provides security for the kids. So don't abandon them. If you have a kid, you have an obligation. The nature of that obligation has nothing to do with being married.
Finally, I can't ignore the big picture: marriage is a mutual agreement to slap on the handcuffs. That doesn't sound very grown-up to me.