Flirt-by date
Just as products have sell-by dates for when the contents are deemed to be inedible, people who fancy themselves as charmers, should have flirt-by dates for when their flirtatious behaviour is deemed to be more than a little off putting. This is most likely the result of old age.
"Did you hear Jane caught John flirting with some young chick again and this time divorce is on the cards"
"Well I guess his flirt-by date is up!"
"Well I guess his flirt-by date is up!"