In my opinion, the reality is that money can change a person. by getting a big win or a large amount of money, of course it does influence thinking, usually people will experience changes when they have a lot of money. This is clearly a reality because in my environment there are cases like this too. People who get big wins tend not to care about relationships or anything else because they feel like they have a lot of money so they think they can have everything with the money they get. with them separating, perhaps because of their respective egos, which are both large, whereas they cannot take a better middle path, only thinking about their own egos, until the decision that occurs is separation.
It's true what you say, maybe it's because of their greed, but in my opinion, if the party who wins can share it well, in the sense that they are already in a serious relationship then everything should be done together. including the victory obtained, if it is discussed properly, perhaps there will be no separation. However, in reality, humans do have the nature of being greedy with their own portions, especially with money. When you have a large amount of money, change or selfishness will definitely emerge.
The thing wouldn't reach the point of separation if they were both serious about the relationship and if they had love and affection for one another, but that doesn't seem to be the case in this situation because they are doing their best to have the money on their own and keep the other person out of it, and from what we can read from the story, the girl/women seems to be more selfish and greedy if she is the one who started all this after the win if what is written in the story is true.
However, this shows that a lot of relationships are based only on certain conditions and compromises and this is proved right when things like these happen.