It's vitally important that health and financial issues are openly discussed, and that a solicitor is engaged to draw up binding documentation before they are married.
My father remarried a few years after my mother's sudden death. Both he and his partner agreed that their estates should be kept separate and that only their own children would inherit. They sold their houses (hers was very small) and he bought a new one for them both which we, his children, would inherit. She gave most of the proceeds of hers to her sons as an early inheritance. So far so good.
However...my dad decided that if he died first, she would be allowed to live in the new house till she died, when it should be sold and the proceeds given to my siblings and me. His solicitor advised against this due to long experience dealing with these kinds of situations, my dad got on his high horse ( how dare you suggest my wife and her family are dishonest etc) and they fell out over it. They'd been friends for nearly 40 years. And that is how it was left.
A few years later came the boom in house prices. Her sons in their wisdom decided that she should never have sold her house when she did, because if she had waited they would have got a lot more money. So they told my Dad they wanted him to make up the difference. Bear in mind that these were two very wealthy men at the top of their professions. They really didn't need this money, but they had convinced themselves they were entitled to it. He, trying to keep the peace, agreed after much hoohah that he would leave a sum in his will for them.
My siblings were hoping that Dad was bluffing, but he did indeed die a few years later, and he had left them the money. My sisters were furious, and never quite got over it. Then we had to wait and see what would happen with the house. She died a couple of years later and her sons did sell the house and we got the proceeds. However, their solicitor's fee was astronomical. One of the sons was a solicitor and my sisters were convinced he'd done some kind of a deal to get something for himself. I really don't know if this was the case, but they did take a ridiculous amount, and by this stage I was so fed up with the whole shebang I had no interest in prolonging it.
Anyway, the point of this long post is that you can NEVER take for granted in these situations that everything will be straightforward and that the other parties involved will behave decently. Nor can you anticipate what may happen; her sons bullying my dad for money was not anything I could ever have imagined. My mother must have been rolling in her grave. But my father was blinded by his grief and his need for a companion.
And for those scolding the OP...it's not about the money, it's about family loyalty and legacy. He may have found a new wife, but all those years with his first wife and his children must be honoured. To not do so is cruel.