I don't know. It may sound sad to you but I have not been in love since I finished high school which probably means that I have never been in love in the first place. I guess this makes me the worst possible person in the world to answer that question. Anyway I will still try.
Many answers comes to mind. The first one is: if you are asking this question you are probably not in love. When you love or like something or somebody you don't ask questions. You know the answers but they seem too hard to admit. Too hard to swallow. It's funny how how we ask so many questions about things we already know.
To me being in love is like finding the missing part of the puzzle, the part that makes it all work, the part that is the opposite of you and still fits perfectly. So, if you feel that way you are probably in love. Here's the catch however. Most people think that when you are in love you will be in love forever. This is not true. Love has an expiration date like everything else in life, including your knees. Being in love and being in love forever are two different things.
As a wise man once said:
"A man is already halfway in love with any woman who listens to him."
So, to answer your question once again - the time when you don't need an answer is when you are truly in love.
While you are waiting you may just as well go lift some weights.