Why is love so inherently selfish?

It’s not always selfish. It’s selfish to live for yourself rather than someone else. Love is taking the hard way over the easy way; love is being willing to be the first person to apologize; to work at your relationship even when you're tired; to be supportive even when you feel like putting your fist through the wall. Being in love often means putting your lover before yourself. If anything, love requires a lot of sacrifice.

It does some searching to fully grasp it.

Romantic love, yes.