It is my experience that they do, and anecdotally what I hear from others.
Within 4 months of my Mum’s death, my Dad was interested in someone else and they have now been together for 10 years.
Nano seconds after our separation, my ex got together with someone else. Really nano-seconds
.
What does it mean - did my ex really not give a shit in the first place, so moving on was easy?