Aquarius are charmers to the core, but you cannot play with their feelings and think its going to actually ends well. Everybody has different ideas about happiness and the means applied to get that happiness are also different.
Due to egoistic attitude (personal interests or selfish means), he does not care whether somebody’s feelings are hurt or not.
Take for example, a boy expresses his love to a girl and girl also reciprocate. After sometime, boy or girl meets some other person who fits more in his or her ideas of happiness (liking), gets attracted to that person leaving the first person heartbroken. In short, those who have no self pinching easily play with the feeling of the other people.