Robert is one of the primary characters in The Awakening by Kate Chopin, and he is best known for being a "summer lover." We learn his history in chapter five of the novel, and we learn two very significant things about him: he is passionless and he is shallow.
Since the age of fifteen, which was eleven years before, Robert each summer at Grand Isle had constituted himself the devoted attendant of some fair dame or damsel. Sometimes it was a young girl, again a widow; but as often as not it was some interesting married woman.
Robert spends his time adoring one woman or another, but neither he nor his adoration are taken seriously. When one of the women he spent two summers adoring dies before the next summer, Robert is dramatically inconsolable, but he quickly chooses another object of adoration because his heart had not really been broken. This is his noncommittal pattern and, until he meets Edna, his way of life.
It might not seem, at first, as if Robert is passionless or shallow; after all, he spends his days being a "devoted attendant." What that means is that he spends his time serving, waiting on, offering words of love to, and mooning over a woman, doing whatever she wishes and whatever he can think of to make her feel as if she is the only significant person in his life. While he does these things for his chosen women, however, he does them without any true passion or love for them. We know that because he does the same things for a different woman every summer. Perhaps the details of his adoring acts change, but they are the same in essence. Fortunately for both Robert and the women, none of them expect or want true passion. These Creole women (and their husbands) are perfectly content with this arrangement precisely because they all know there is plenty of action but no real emotion.
This is all fine until Robert meets Edna, and then we learn one more thing about Robert: he is unable to commit himself to a true love relationship. Edna is not a Creole woman, and she does not understand the "rules" of this kind of adoration. Because she is in a marriage relationship which seems more like a business arrangement (she is to "manage" the household affairs and the children while Leonce does as he pleases), Robert's attentions fulfill a need and she falls in love with him.
The complications and ramifications of Edna's love for Robert and his inability to commit himself to her, despite the fact that he has "forgotten nothing at Grand Isle," lead directly to her death. He leaves her to go practice his careless adoration in Mexico; when he returns, she tells herself "He loves you, poor fool." But she is wrong, at least in thinking that he will be with her. He visits her once and she wakes up hopeful the next day; however
Robert did not come that day. She was keenly disappointed. He did not come the following day, nor the next. Each morning she awoke with hope, and each night she was a prey to despondency.
Robert acts adoring and makes implied promises without ever giving his heart because he is incapable of committing to a loving relationship. To be fair, this is a perfectly acceptable arrangement to the Creole women (and men) of the Grand Isle. No one minds his adoration games because they all know Robert will play by the rules and maintain a shallow, passionless relationship. When he meets Edna, however, he can no longer play the same passionless, shallow, noncommittal game--at least not without consequences.
Robert is a player and he goes around flirting with married women. He likes to fool around and mess with these women's heads just to keep himself entertained. The women play along with him and actually give in to it because they have nothing better to do. Edna on the other hand takes it to another level and they start catching feelings for each other. He was her playing with her emotions to the point it got out of hand and she commits suicide because she gets so attached.
He is not taken seriously by the women at Grand Isle because he is know for his flirtatiousness with married women in the summer. Edna takes him seriously and begins to develop feelings for him. This suggests that he is flirtatious and a overly nice person.