I don't think Manchester United will sell Bruno Fernandes because he's the club's most important player. Moreover, if Galatasaray makes an offer below 40 million, Manchester United will definitely reject it. So, I strongly believe both Manchester United and Fernandes will reject Galatasaray's offer.
The real question would be why is a player like Bruno Fernandez be linked to Galatasaray, because I think it spells a bad omen for his caliber of player, especially when he is in a good form, he is the best player of Manchester United right now and it doesnt seem like he is playing poorly or badly right now.
However the final decision would come from Manchester United and the player himself if he still want to continue with Manchester United, considering how he is playing and when his contract is going to expire, and if he is going to be offered a new contract, I think Bruno Fernandez has to make all that decisions himself because it might be very terrible for him if he doesnt perform well next season probably if he decides to stay just like he rejected Saudi Arabia Approach last Summer.
With how Bruno Fernandez carries Manchester United in his head, I don't think he will want to leave Manchester United now that it looks like there is light at the end of the tunnel for them. Bruno Fernandez that has been there even when the club was looking like all hope were lost and he didn't leave, is it now that they are about to taste the champions league next season that he will leave. The only thing that can push him out of the club is if the club management ask him to leave. Apart from that, there's nothing that will pull that nigga out of Manchester United.