Symbols
An obvious choice of symbol is the heart but you can choose to decorate it with names, flowers, flourishes of color or even birds and bees. A good variation the heart theme is a broken heart coming together into one to show the healing of a rift with love. Other symbols representing love could be crossed wedding rings.
Names
Having the name of your significant other regardless of how much you love them could be risky. Too many people have been completely and truly in love only to separate later down the line and have to deal with a painful reminder of the past. The risks are just not worth the reward but that doesn't mean you can't represent in some fashion your significant other. A tattoo of their birth sign, crystal, favorite color or something similar can represent them. Yet if you were to ever split up it can come to mean something else.
Mythology
Cupid the Roman God of erotic love and beauty is a popular design when firing an arrow through a persons name or even a heart. These are often depicted in the form of a child but there's nothing that specifically states Cupid was a child so you can opt to have an adult cupid. Although human forms are rarely popular. Another great tattoo is the goddess of love itself -Venus. Venus could be represented as a human form such as the classic "Birth of Venus" by Botticelli or even the Zodiac symbol for Venus.
