When my, much older cousin died, her only child, who lived abroad, asked us to 'keep an eye' on her elderly father.
My husband and I would visit, sometimes we would go out for lunch, and I would phone him regularly, just to check up on him.
About 2 years after my cousins death, my husband died suddenly. Within a few weeks of his death, my cousin's widower was suggesting I go on cruises with him or move in with him, have weekends away etc.
I felt really uncomfortable going to visit on my own, so I decided to stop all contact.