Haaland needs to get used to the pressure. Wherever he goes, it is already clear that it will be a top club and there the pressure on him (in terms of expected results) will be constant. However, I support him in that he openly declares some problems - this will be a good signal for those who put pressure on him to stop their actions.
He did not play for big clubs and did not play in any international big tournament, Euro or World Cup. International tournaments can be one of biggest regret for Haaland and he might be another Giggs who did not achieve big thing with Wales.
Haaland is one of best strikers now and in future but I am very doubtful that he can bring Norway to World Cup or Euro. Even Norway can get in, they might not go to far in big tournaments.
Haaland is young and haven't had any prior experiences in major club so yeah can understand him being unable to handle the pressure. But yeah it is also true that this is normal but Dortmund also shouldn't force him like that. He earlier send out signal one or two year ago when asked about the next club and he said that he has contract with Dortmund right now and he respects the club so won't get away suddenly.
Haaland will leave and Dortmund know that. They are a club with tradition to grow up young players and sell them at expensive cost to get profit for club's balance sheet.
Therefore, it is in their plans and they do prepare for Haaland transfer. I think that initially when Dortmund signed with players like Haaland, Sancho, Bellingham, etc. they did have plans to get profit in future by big transfers.