What is the cause of a specific saddle chaffing?

Hi everyone!

I did a 120km ride yesterday, and I experienced chaffing after 60km. Why I’m kinda dumbfounded is that I used not to experience such acute chaffing for longer rides, last year.

The chaffing doesn’t occur right at the seat bones, but on the outer zone of it, extending toward the outside of… my butt cheeks? I felt like the sides of the saddle might be rubbing, but apparently it wasn’t, and I didn’t feel the chamois did move….
Of course I applied chamois cream beforehand, but directly on my skin.
Saddle is a Fizik Tempo Argo R5 143mm. My seat bones are roughly 130mm and I’m 69kg.

Could it be that my saddle is actually… too narrow?* Or am I completely missing or misunderstanding something?

What happened since last year: - my saddle was raised. I was too low, which probably amplified patella issues. I don’t experience them anymore while cycling, because I was really too low, according to a local bike fitter. I raised it with him, and he reckons I could go up less that 5mm. - my saddle was also put forward a lot. I feel I could still put it more forward by 2 or 3mm (guesstimating I recon) - my cockpit was raised accordingly by a whole centimeter, and I could add maybe 3mm in height for that MAMIL-dad look. - I tried a new bib (Rapha Cargo bib), which felt nice on rides of 60km or less. My older bibs from Isadore were starting to feel uncomfortable… after my saddle height-and-fore change.

Thank you all for your input!