There are many conditions and contingencies with most real estate purchase contracts, but I feel confident assuming that romantic relationship continuity is not included in any state's promulgated contract.
The terms are legally binding, and if the seller does not perform as agreed, the buyer may seek a legal remedy (and vice versa). This can involve a law suit, or mediation, or any other remedy as provided for in the contract or by state law. Hasn't your broker provided guidance on your possible recourse? You can always seek legal counsel, but is it worth it? Only you can make that decision.
All the best!