It's a slightly special sort of heart shape there, with the crown in the middle, very like the Irish Claddagh Ring symbol.
The crown on top symbolisies the sacredness of the love and enduring friendship it represents.
"The secret of our being, is not only to live, but to have something to live for." (Dostoyevsky)
(I've just got that from the back of a Claddagh plaque I was given.
)