Marriage is a complex and binding contract that for two high earners is a tax disadvantage. The most prominent benefits I’ve learned are some situations around visitation rights, and avoiding being compelled to testify against your spouse. It comes from a very dubious history of the husband essentially owning the wife. The “commitment” of the legal marriage obviously doesn’t prevent people from falling out of love or breaking up, not that it should – if one partner stops loving another they will still leave the relationship one way or another. So, why marry — besides “tradition” and “society wants you to for whatever reason”?