3. Do not indulge a sexual misconduct
(It is not possible to show a picture to illustrate clearly this precept)
The third precept is to not indulge a sexual misconduct. That means if you have a "boyfriend" (girlfriend) you will have to be faithful to him (her) and have no one else. It is very unsound to live a cheating life. It compel you to lie all the time. This can bring about hugely sorrow. Moral hurting is much more aching than physical pain.
As in honesty, virtue in love is something very important. If you really want to know true love with a boy (girl), or at least if you only want people to love you sincerely you have to never play with other people feelings.