A JV built around a single purchase contract can die the moment that contract expires

Non-circumvention is the clause doing the work you thought the whole agreement was doing. A deal-specific JV that identifies the venture by reference to one purchase contract ends when that contract ends. Protection on the seller relationship has to be written as its own obligation: name the seller, name the property, and cover any acquisition by either party or an affiliate for a stated tail period, six or twelve months being common. Whether a court enforces that tail depends on your state's law and on how narrowly it's drafted, so have an attorney licensed in your state write or review it.

Two things in your numbers. You funded 2,500 of nonrefundable earnest on a deal where the exit depended entirely on his buyers. That is your capital covering his performance risk. Cost allocation should be symmetrical, either both sides fund in proportion to the split, or the funding party recovers that money off the top before any split.

The close date is the mechanic that made the rest possible. A contract with no unilateral extension right, on a seller who has direct contact with your partner, leaves you nothing to hold at day 45. Extension language costs nothing to ask for at signing and is the cheapest protection in the file.

My answer assumes your partner had direct seller contact well before expiration. If he only spoke to the seller after the contract died, the facts read differently and your argument is stronger, and that is still a conversation for a lawyer rather than a forum.

I'd put the cause somewhere other than where you have. The paper failed you, agreed. But the deal was underwater on exit risk from day one. You underwrote the acquisition and let him underwrite the disposition, and you never saw evidence of the buyer pool. Did you ever get names, a look at his last three closings, or a single proof of funds from a buyer at that price point in that submarket? A 4 unit at 96k in a soft submarket is a narrow buyer set. If he'd shown you two live buyers at signing you'd have known the 45 days was tight and you'd have negotiated the extension. The non-circumvention clause would have paid you 7k after a fight. Buyer verification would have closed the deal.

This is the question I'd have been too embarrassed to ask in a room, so I'll ask it here. Did the seller ever know you existed?

Because reading your post, the seller met his entity, signed his paper, got the proof of funds from him, and closed with him. Your lending contact handed you the address. Everything after that was his relationship. So when the contract died there was nothing for him to circumvent in practice, he just kept talking to a person he'd been talking to for nine weeks.

Which means the fix isn't only the tail clause, though get that too. Be in the room. Be on the emails. Be at the kitchen table or on the call, introduced as a partner, so the seller has a reason to think both names are part of the deal. If you'd been in that conversation, the day 46 phone call from your partner alone looks strange to the seller and he might have called you.

I've watched a JV where the acquisition guy did exactly that, cc'd on everything, and when the first contract fell apart the seller called him, not the other guy. Same paper as yours, roughly. Different outcome, because the seller had two humans in his phone.

Same lesson I keep hitting on tenant screening, in a different suit. The document only helps if you're actually in the relationship it describes.