when do you know that it's true love?

You don't know... and you never will... because there is no such thing as ever lasting true love. Love is something which happen when two people feel happy to be together. But once you are in love with each other... you have expectations of things remaining the same. You want those reasons why you fell in love the first day to remain there until the day you die. This simply won't happen. It is an impossibility. That is why people fall out of love. Things change everyday... and you need to adapt to them. If you want to stay in love... your love needs to be build on some very strong foundations and very strong values. Falling in love with someone... for the sole reason that they look sexy... is no more than lust... and it is doom in the long run. This is a common mistake amongst teenagers. Furthermore... your lover needs also to be your best friend. Love without friendship is doom. Best friends don't argue and forgive each other's mistakes. They support each other in every way and are always there for each other. That's true love... if you can find such a friend.