Looking for the story I read a while ago

[xcalibre2603]

I read a story a little while back where the theme is of incestous car sex between mom and elder son near a beach in the way to drop the son to college. While this is going on the husband and second son are waiting in college dormitory waiting for the wife and elder son to join them. A friends group of second son watches the mom and son having sex in a car without knowing the couple engaged in sex are mother and son. A girl present in the group recognises the mum and sends a message to second son but she does not know the boy engaged in sex with mum.

Mum is a real estate agent or something.

If anyone recognises the plot or knows the story name. Reply.