Many older divorced or widowed men and women are in the same boat. You're probably not desperate enough to stalk your neighbors, or to go looking for friends with benefits in all the wrong places (bars come to mind).
Should she have cut it as soon as she felt that she was developing feelings for the guy? should she continue seeing the guy, enjoy dating him as much as she can while she can, and not worry about the outcome of the situation too much, without thinking about the future too much?
I don’t think any woman can find an absolute and unequivocal answer to this question, and I frankly don’t believe that such an answer exists, as it would heavily depend on that specific woman’s goals and needs at that specific point in her life.
An older woman might have the greatest time of her life dating an energetic, exciting, attractive young man, but she is also likely to feel that she is wasting her time being with a younger guy and knowing that it is not going to turn into a long-term relationship, instead of pursuing a relationship with a man with whom she could establish a family and have children in the nearest future as the biology would dictate to a woman who is aware that her biological clock is ticking.
But then again – not every woman wants family and children.
It is not rare to see a younger guy and an older woman date and have a very intense sexual and romantic relationship, which defies the traditional “older man, younger woman” set-up that we are used to seeing. First, the fact that such a dating situation is still somewhat taboo makes is all the more enticing and exciting.