Co-owning a home indefinitely after divorce?

After divorce, can my ex and I continue to co-own our marital home indefinitely, where his name stays on both the mortgage and deed, but he no longer lives there? Is this type of arrangement able to be outlined in a separation agreement, or would we need some sort of special real estate or business contract in addition?

Basically, he left me for another woman, but doesn’t want the kids to have to move from the house we just built. He says he’ll continue to pay half the mortgage for as long as I own the home (so even beyond when alimony would run out), and will defer to me on whether/when to sell. He does not want to sign a quitclaim to get off the deed because he wants to take his equity whenever we sell. He’s viewing it as an investment.

Yes, this can be done and the specifics can be outlined in a separation agreement. Generally this sort of arrangement is not advisable because the purpose of a separation agreement is to divide the marital property but leaving assets and debt in both spouse’s names does not actually divide the property. You may want to consider refinancing the mortgage into just your name and taking care of the deed and equity issues beforehand in the separation agreement rather than waiting until potentially years after a divorce.