LOVE...
i guess love is a lot of things. there is no line to cross, there is no one answer, no one definition. there is both good and bad. sometimes you think its irrational, and yet when you decide to love somebody, in whatever form or way, you know its the sanest decision you will ever make.
i think you'll know that you love somebody, and if that somebody loves you back. just like when you know that you're over someone and you're ready to move on. you don't need to be sure. if you have doubts, don't fret. even most married couples have doubts. but i guess the point is not NOT having doubts, because they'll never go away. the more important thing is asking how do you deal with them? do your doubts affect your fundamental beliefs? are you willing to comprise those?