One thing she definitely doesn't quite understand is that is simply an 'overuse' injury. Mental stressors do NOT affect the bone. That aspect can affect a lot of things, but it will clearly not cause a stress fracture.
ArmchairMD diagnosis aside...
Mental stress won't break a bone, but mental stress leading to careless workouts/form can contribute.
I would guess that 'careless workouts' could lead to this, but it doesn't seem likely that her bio-mechanics suddenly deteriorated. Much more commonly, lots and lots of workouts lead to sf's (and bad luck).......and occur more frequently with certain additional risk factors.
*Established risk factors for Stress Fractures
Prior stress fracture
Poor bone health (osteopenia and osteoporosis)
Substantial increase in intensity or volume of activity (eg, military boot camp)
Decreased physical fitness (poor muscle strength or endurance)
Dietary disorders (eg, insufficient calcium intake, vitamin D deficiency, eating disorders)
Family history of osteopenia or osteoporosis
Poor running biomechanics
Menstrual irregularity in females
Low body mass index
Prolonged glucocorticoid use
Factors of uncertain risk
Shoe type; Worn-out shoes
Foot anatomy (eg, extreme high arch)
The combination of low energy availability (with or without an eating disorder), menstrual irregularity, and low bone mineral density comprises the "female athlete triad" and places a woman at greatly increased risk of stress fractures. Even women without the entire syndrome but with an elevated female athlete triad cumulative risk score demonstrate an increased risk for developing bone stress injuries.
I do not know her at all and do not know what other things are going on. I don't read their instagram and don't follow pro athletes on social media. It is good that her bone mass is normal. It is bad that she now is at risk for future sf's.
I'll go back to my (arm)chair and get some popcorn for the next round-