Here we have the age old situation with affairs of the heart. You can never know love unless you are prepared to take the risk of heartache if things don't work out. Who can resist the lure of the reward, even if danger is clear beforehand?
The chocolate heart symbolises love and sensual pleasures. The bright, fresh rose petals in front of where the rose grows from the front of the heart signify blossoming love. The dull, dead rose petals behind where the knife has penetrated the back of the heart signify the emotional trauma of failed love. The knife also reflects those situations when the danger in pursuing the liaison is clear even beforehand.