What are the best methods (questionnaires/tests/etc) to measure ability to love?

So far I see those

1. Light Triad Test (described in Scientific American)

2. Big Five personality traits (OCEAN model) - especially its agreeableness subscale (friendly/compassionate vs. critical/rational)

3. HEXACO model of personality structure - its agreeableness subscale + Honesty-Humility subscale

I realize that "love" is a very broad term, which is poorely determined, but anyway let's give it a try! At least let's try to factor out some components of love (loving person) and try to measure these separate components.