Context, I'm 30 now and i will find women my age and up attractive, but 15 years ago a 35 year old women would never have been attractive to me.
As I've aged younger women are less and less attractive (thankfully)
But when I'm 60 will 60 year old women be attractive to me?
There isn't a limit, your tastes on what you consider "attractive" will change over time. When one is young one only thinks on reproduction, and the older one gets, the more prevalent just having someone who you enjoy keeping you company.
Depending on your definition of "young", what it actually is is that young people mainly think of fucking.
Which looking at it on a purely biological lens is to satiate a need to procreate.
Speaking in terms of ultimate (evolutionary) causes, obviously, but on a proximate level of, for example, what the people in question actually think and feel, as well as the practical outcome given the accessibility of effective contraceptives, it has nearly nothing to do with reproduction.