This 100%. Eleven years into our relationship, with now a 7 years old kid. We were raised in non-religious families and we are non-religious, so why get married? Why then bring the "religion of the state" in our lives? We don't need no public servant to officially declare us married. We don't need no state-endorsed paper. We don't need no more administrative burden.
A breakup would, indeed, be bad enough in itself to then add insult to injury by having lawyers on both sides competing to see which of them has the sharpest teeth while they'd be bleeding us dry.
Just screw that entire system.