Is this example of rebounding

One of my friends has a problem. She believes her ex who controlled her, went on the rebound after he broke up or freed her. Kayla, as I will call her, dated Brent for three and a half years. When they first started dating, Brent would make comparisons to his ex named Mindy. He would tell Kayla Mindy did this, Mindy did that, etc. He even told her he would not date her at first because he was afraid to date. Oh yeah, Mindy dumped Brent three years previously before. So Brent did not date for three years, according to him. Brent was afraid to date Kayla because he did not want to get hurt. Brent gave Kayla the impression he was still in love with Mindy who got married a few months before. Either Mindy wanted to make him mad or try to be friends, but she ended up inviting him to the wedding. Of course he did not go, and the fact he was invited really set him off. Kayla said Brent would talk about Mindy as if they were dating yesterday.

Now for Kayla and Brent. Though he still talked about Mindy, he would cry when Kayla tried to break up with him. He told her once he had a wall around his heart and Kayla melted that wall. Out of guilt and immaturity, Kayla stayed. However, the breakup talked lasted for another two years UNTIL Brent decided he wanted out of the relationship the night he was going to propose. He had a ring and everything, a ring Kayla picked out. Kayla is sad but looks forward to the future. Brent calls her up about a month later and says he is dating. Kayla doesn't care, she is more mad he is acting immature with his business-like tone. The day this happens, he tells her he is never getting married. Then he says to get out of his life. Kayla is hurt, but moves on. Brent calls, one week before going to another college, asking her if she is dating anyone. She knows her ex is trying to get a rise out of her by telling her he is in a serious relationship, but my friend manages to stop him.  Six months later, Kayla meets a real man who loves her for who she is. When Brent's mom finds out about the new boyfriend, she tries to be Kayla's friend, or pretends nothing happens and calls for a quick chat. One year after dating, Kayla got engaged to Tom, the man who loves her for who she is. Then three months later, Kayla learned Brent was engaged too and getting married two weeks after her wedding. Oh yeah, the ring she picked out was also on his ex's fiancee's finger. Oh and the ring did not cost that much. Kayla could not talk to Brent because she was still afraid of him after his outbursts the summer of her freedom.

Is this a case of rebound for Brent? It seems Kayla is annoyed that Brent got married for rebound reasons. Was Kayla the rebound girl and Brent's wife was the rebound wife.  I don't know what to tell her.