Bill and Melinda Gates have had a decades-long agreement that the Microsoft boss could go on a yearly vacation for a long weekend at the beach with his venture capitalist ex-girlfriend, the Mail reported.

The bizarre arrangement raises eyebrows now that one of the richest couples are going through separate ways after 27 years together and building a $130 billion fortune.

Bill, 65, and venture capitalist Ann Winblad, 70, dated in the 80s but broke up in 1987, the same year he met future wife Melinda. Ann was reportedly more ready for marriage than Bill as he worked day and night to build his billion-dollar Microsoft empire.

Nonetheless, Bill and Ann maintained a friendship, and in a 1997 piece in TIME Magazine, Bill said “When I was off on my own thinking about marrying Melinda, I called Ann and asked for her approval.”

Ann approved and the former lovers – with Melinda’s blessing – kept their yearly vacation alive, with the Microsoft boss spending a long weekend with Ann at her beach house on the Outer Banks of North Carolina.

The pair spend their getaway taking walks on the beach, riding dune buggies and hang-gliding. “We can play putt-putt while discussing biotechnology,” Bill said in the 1997 interview.

“We share our thoughts about the world and ourselves. And we marvel about how, as two young overachievers, we began a great adventure on the fringes of a little-known industry and it landed us at the center of an amazing universe,” Ann said.

Both Melinda and Bill posted the same joint statement about their divorce on Twitter Monday, and in papers filed in Washington state, Melinda, 56, described their relationship as ‘irretrievably broken’.