When DP got divorced he agreed to be a home owner guarantor for his ex so she could rent somewhere (she never worked). Since then, 5 years have gone by, he has sold that particular house, didn't own a house for a while and then bought another house with me - we are joint owners of it. I used to panic that if she didn't pay her rent we'd have to pay it for her but since time has gone on and the original house ownership no longer exists and his current house is xo-owned - Aibu / naive to assume that his guarantor status would no longer be enforceable should she stop paying her rent?