Paula Badosa spoke about the mental fatigue that tennis has on players using the example of some of her colleagues.
Many things make it very hard, chiefly the constant travel which has you away from home for 90 % of the year. That's a tough thing to overcome for a person, especially as it accumulates over the years.
Somebody who is 25 might have been in that grind for over a decade despite being a fairly young player. That's what Badosa referenced when talking about the sport, noting the examples of Ashleigh Barty, who retired fairly young.
On the other hand, Naomi Osaka took a break from tennis at a similarly young age, but both have been in the sport for over a decade. That sort of fatigue builds up over the years.
It's not by chance. It is no coincidence that you see Ashleigh Barty retiring at 25, Naomi Osaka [four-time Grand Slam champion] going through a mentally difficult period. Then Garbine Muguruza… It is no coincidence. This is a very demanding sport in which we are forced to play more and more weeks and you are very exposed. It doesn't surprise me.
Badosa experienced a pretty tough season herself, missing much of it because of the injury. She was able to fill that time up by traveling with her boyfriend Stefanos Tsitsipas, making the whole grind a bit easier, but that wouldn't have been the case if she played.
If she played, she'd spent more time away from him than together because the Tour rarely overlaps in the calendar. It's a very lonely life, and very few people can handle it.