In the long run, if it's true that "he who cares less, wins in the end".

It serves you no benefit to care about anyone else but yourself, it all goes back to who's more invested.

Taken to an extreme, be a cold, heartless sociopath. On the opposite end be a literal empath.

I've been on both ends of the spectrum, currently trending towards being more of an empath.

I believe the real key is, be no-more invested than the other party is, an appropriate amount of equal caring on both sides depending on length of time together.

If the other pulls away, pull away further, mirror her actions and attitude, and adapt to her behavior, treat her the exact same way she treats you.

Maybe you could sum up TRP as the golden rule "Do unto others..."

At least that's what I've always done.