Was asked, "How do you know when it's the one?"

1. Ethics - same idea of how people should be treated. (Degree of selfishness vs altruism. Degree of honesty. Etc.)
2. Comfort - can you fart around them? Have you reached the point where you're really being how you actually really are? And them also?
3. Trust - self explanatory
4. Acceptance - are you still keeping a tally of their positives and negatives and comparing to others? Or do you accept the person as they are, and plan on making things work with them?

Applies for any actual real friendships also.

(I guess actual attraction and a few additional odds and ends matter, slightly.)