IF TRANSLATED literally, gerontophilia is the condition in which younger people are predominantly interested in, or only able to, make love to older people.
If an older partner is essential for them to achieve sexual satisfaction, it would be included in one of the paraphilias, or perversions as they were once called in less politically correct days.
Gerontophilia is not now usually used to describe the love of a younger woman for an older man, or vice versa. It has always been more socially acceptable for older men to have younger partners and in some parts of the world was considered entirely usual.
Now gerontophilia tends to be used only to describe the rape or sexual assault of a woman over 50 by an appreciably