For a voluntary sale of the whole house, the deed and any applicable court order show who needs to take part. If a spouse is legally authorized to sign for the other, or a court order addresses the sale, the title company needs the documents that show that authority.
If you own the house as tenants by the entireties — a form of joint ownership for married spouses — both sign the sale papers while married. After divorce, Pennsylvania law under 23 Pa.C.S. §3507 generally treats that former entireties property as equal one-half shares unless a court order under that chapter provides otherwise.
The title company can review the deed, recorded ownership, required signatures, and closing documents. A Pennsylvania attorney can explain how a divorce decree or court order applies to your situation.