Sigh... This topic has been discussed here so many times. Yet there's always someone who wants to start a new thread to let everyone know that they consider people not accepting their rematch requests bad sports, cowards, rude, disrespectful, <insert your favorite insult here>, etc.
No one owes you a rematch. No one owes you an explanation of why they refuse your rematch request: https://support.chess.com/article/1342-is-it-rude-to-refuse-a-rematch-request
Refusing a rematch used to be a trend, rather a minority, it has now become the rule, although to be precise, the statistics clearly show that most players are more likely to accept a rematch if they have lost... and to refuse it if they have won. Even if they won with the whites. I can't quite figure out the logic, or the motivation. Especially since those players who refuse the rematch mostly stay online, and play other players. But it seems to me that one of the interests of this game is precisely to learn to analyse your opponent's game and to learn from it for the following games. What does this lack of fairplay, this lack of respect for the opponent, encouraged by anonymity, really reflect? What do professional players think about it? Couldn't we foresee a mini-tournament format on chess.com, which we would call for example best of three or best of five... ?