Feelings = love, longing to be with them, or strong liking.
Relationship = not a fling, but they are not engaged or married either.
What if the person they're with is your close relative (say, a brother or a sister)?
If feelings are okay, should they be acted upon? (Not necessarily trying to break the relationship; rather, confessing your feelings to the person.)
If you were the one in love, would you confess?
If you were the person they're with, how would you react to the fact that someone else has feelings for your SO?
Strong opinions are welcome :)