I definitely understand your point, because Real Madrid will not do that because since they usually meet in the Champions League, they don't want to see any of their great players playing against them. As we all know Paris Saint-Germain is a big team and they can afford any player they want no matter the price, take a look at how Dembélé humiliated Barcelona as if he was never there, I think Real Madrid learned from that that is why they will not let any of their great player to join them.
Güler is a great player and Real Madrid are enjoying his moment, he's very young and also talented and I don't think they will let go of him and even though they will not let him go to PSG. Güler will be very useful for Mourinho because of how talented he is.
Dembélé's story is a bit complicated, because in any case when he was at Barcelona he was a spoiled kid, or at least he acted like that, given that he played Play all night and was late for training. As a result, the club and the fans themselves became a little fierce against him, perhaps exaggerating a little. In fact, his revenge was very evident and certainly brought him a certain amount of enjoyment.