Hi Rin!
Thanks for sharing so many insights about you're life.
Rejection is tough, no matter whether it is a relationship orva job.
The best thing you can do (and what you already did) is to draw the consequences and move on to the next opportunity.
Being rejected is not about you, it only means from the many many candidates they found someonen who is a better fit for them.
In my opinion those several round interviews are very often flawed, and they are not really finding the perfect match.
Heads up and keep on going. 😊👏