Has there been a situation like that in the past that a player retired after wasting matchpoints ? How will you count it today ?
Gonzo had 7 matchpoints (*4-5 15-40 and three advantages and *5-6 15-40)
Not a 21st century match, not even Open Era, but the most high-profile match to feature this was:
Wimbledon 1960 QF - Neale Fraser def. Earl Buchholz 4-6 6-3 4-6 15-15 ret. (saved 6 MPs)
Fraser was the #1 player at the time, his opponent a 19 year-old who shortly rose to prominence that year after winning several junior slam titles. The young American has already beaten the Australian twice coming to this match, and was clearly the better player on the day, holding with ease throughout the 4th set, but an ankle injury, cramps and heat exhaustion forced his retirement.
Fraser went on to win the title, beating Laver in close 4 sets in the final.