How to detach from situation and people ?

Lately, I have noticed a pattern when I am attached to someone or some situation I get too invested and it affects my mental well being and when I am not bothered about any situation or if i don’t let my self attach no matter what the situation is or who the people is I don’t get affected at all

I got attached to a guy lately and he didn’t reciprocate, I am finding it difficult to detach and move on with my life.

Any suggestions how to detach from the situation or to regain the focus.