Adults Only

Legally binding relationships should be able to transcend the rigid two-person nuclear family template that dominates our current legal system. That model simply doesn’t work for everyone anymore, and it’s time we offered people the freedom to define their own relationships on their own terms. The law is already inching in this direction through cohabitation agreements, domestic partnership registries, and court rulings that recognize nonmarital contracts, but those tools remain piecemeal and optional. What we need is a broader framework that lets adults craft legally recognized arrangements tailored to their actual lives—whether that’s platonic co-parenting, shared housing without financial entanglement, or something entirely new.^1,2,3^

Why the current model falls short

For decades, the legal system treated marriage as the gold standard, offering automatic rights to property division, inheritance, healthcare decision-making, and child custody. Unmarried couples—whether romantic or platonic—were left in a gray area where courts often refused to enforce agreements between them, especially when sexual relations were involved.^4,5^ The landmark California case Marvin v. Marvin began to change that by holding that financial agreements between cohabiting partners could be enforceable if they weren’t explicitly tied to the exchange of sex.^1,3^ But even today, many states impose high evidentiary burdens to prove such agreements, and without a written contract, cohabitants often have no legal rights at all.^6,3,7^

The result is a patchwork of protections that varies dramatically by jurisdiction. Some states recognize “de facto parents” and grant custody rights to non-biological caregivers, while others still presume that long-term cohabitation with a child creates a rebuttable “de facto marriage” after four years.^1,8^ Domestic partnership registries exist in places like California, granting limited rights similar to marriage, but they’re not universal.^9^ In short, the law is catching up to modern family structures, but it’s doing so unevenly and reluctantly.^2,5^

What customizable relationships could look like

Imagine a system where any group of adults—romantic partners, close friends, or extended kin—could draft a legally binding relationship agreement that spells out exactly what they share and what they keep separate. These agreements could be as narrow or as broad as the parties want, covering housing, finances, childcare, healthcare directives, inheritance, and even how to unwind the arrangement if it ends.^3,8

Here are a few concrete examples:

• Platonic co-parenting: Two best friends decide to raise a child together. They live in the same house, split childcare duties, and share legal custody, but they keep their finances completely separate and do not have a sexual relationship. Their agreement outlines parenting schedules, decision-making authority for education and healthcare, and a plan for custody if one person moves out.^3,5
• Financially intertwined platonic housemates: Three siblings pool resources to buy a home where they’ll live long-term. They contribute to a joint account for mortgage, utilities, and repairs, but they retain separate incomes and inheritances. The agreement specifies how the home will be sold or divided if one sibling wants to leave, and it includes rights of first refusal for the remaining occupants.^6,10^
• Romantic but nonmarital partnership: A couple chooses not to marry but wants many of the legal benefits. They register as domestic partners (where available) and sign a cohabitation agreement granting each other healthcare decision-making rights, inheritance rights, and equitable division of property acquired during the relationship. They also include a clause opting out of any state-imposed “de facto marriage” presumption.^1,2,7^
• Multi-generational blended household: An aging parent moves in with their adult child and the child’s spouse. They agree to share caregiving responsibilities for the grandkids, and the parent contributes financially to household expenses. The contract addresses how the parent’s care will be funded if they become incapacitated, how the house will be handled after their death, and what happens if the couple divorces.^8,7^
• Chosen family network: Four unrelated adults—two platonic friends and a romantic couple—form a “family unit” for mutual support. They share a large property, rotate meal prep and chores, and rely on each other for emotional and practical support. Their agreement includes provisions for emergency decision-making, shared ownership of vehicles, and a buyout formula if anyone exits the arrangement.^2,10^

How to make it work legally For these agreements to be enforceable, they need clear rules and judicial respect. Here’s what that could entail:

• Voluntary, written contracts: Like prenuptial agreements, relationship contracts should be in writing, signed voluntarily, and ideally reviewed by independent counsel to avoid claims of coercion or misunderstanding.^6,4^ They must include valid consideration—something of value exchanged—that isn’t sexual services, since courts still strike agreements that appear to trade money or support for sex.^1,4^
• Opt-in registration: States could offer a simple registration process (similar to domestic partnership registries) that grants basic rights while allowing parties to customize additional terms. Registration would provide evidence that the agreement exists, reducing the high evidentiary burdens courts currently impose.^3,7^
• Clear exit mechanisms: Every agreement should spell out how to dissolve the arrangement—whether that’s selling property, dividing assets, or transitioning caregiving responsibilities. This prevents protracted court battles and ensures everyone knows their obligations upfront.^6,10^
• Recognition of diverse caregivers: Laws should expand “de facto parent” doctrines so that non-biological, non-romantic caregivers who form strong bonds with children can seek custody or visitation rights without proving a marital-like relationship.^5
• Uniform standards: A model like the Uniform Cohabitants Economic Remedies Act of 2021 could provide consistency across states, ensuring that cohabitants—sexual or not—can bring claims for financial support or property division upon dissolution.^4

Why this matters

The nuclear family isn’t disappearing, but it’s no longer the only viable way to organize life. People are cohabiting longer, forming blended families, and building “chosen families” that don’t fit traditional molds.^2,5^ Without legal tools to recognize these arrangements, too many people—especially women, LGBTQ+ individuals, and low-income households—face instability when relationships end or when they need to make urgent medical or financial decisions.^5,7^

By allowing customizable, legally binding relationships, we’d reduce conflict, protect vulnerable partners and children, and acknowledge that commitment and care aren’t exclusive to marriage. The law is already moving in this direction—cohabitation agreements now protect millions of unmarried couples, and courts are slowly abandoning antiquated moral objections.^2,5,7 The next step is to make these options accessible, enforceable, and respected across the board.

In practice, this means anyone could sit down with the people they trust most—friends, lovers, relatives—and draft an agreement that reflects their actual life. Share a house and childcare but keep finances separate? Fine. Mix money and property but stay platonic? Also fine. The point isn’t to force everyone into a one-size-fits-all model; it’s to give adults the freedom to build relationships that work for them, with legal certainty when things change.^1,6,10^ That’s not just a nice idea—it’s a practical upgrade to a legal system that’s long overdue for a remodel.^2,4,^7