Has anyone EVER mentioned in season 1 how that last time Crowley ever interacted with Aziraphale before the bookshop fire was after he hung up on him. From his perspective Azriaphale called, Crowley outright ignores him for probably the first, and later finds what he thinks is the crime scene of his best friend (and more). Crowley didn't answer once and lost everything.
Now that you're in tears, allow me to get you sobbing: Aziraphale has repeatedly ignored Crowley, hesitated to answer, and fought against him. Now, imagine you're Crowley and for the first time you understand what you want and need and you dare to ask for it. You hype yourself up to ask for more, push yourself to be vulnerable. Then, you are interrupted and cruely gutted through miscommunication and misunderstandings and conflict of interests and the toxic manipulation of outside parties. You realize you've lost, and you're desperate and you're feelings are too big for your words and you are somehow grieving something that hasn't really ended but it falling apart between your fingers. So you call one last time, you pull the most unfair and cruel stunt you can because you can't do anything else to show your love. You need him to understand the gravity of it all. You call out to him, pleading. And he doesn't reciprocate the one consistent thing you've done for 6,000 years minus one event that almost lost you everything. And you lost it again anyways.
David Tennant being a lifelong Doctor Who fan who was inspired by the show to act, becoming the Doctor and Ncuti Gatwa who watched David Tennant and was inspired to act, playing the Doctor opposite David’s Doctor is the most beautiful thing
The Doctor: He [Isaac Newton] was, wasn't he? He was so hot. Oh, is that who I am now?
So what personality trait of his new regeneration is the Doctor mildly surprised by here? He doesn't sound shocked, but it seems to be enough of a difference to mention out loud. A lot of people seem to be interpreting the that as referring to being into guys. To be fair, I think that's how Donna understands it in her next line.
My understanding of the line is slightly different. Feeling attraction to men (along with other genders) is nothing new to the Doctor. Nine and Captain Jack Harkness kissed full on the lips onscreen! Look at any interactions between Ten and the Master. Consider that changing gender presentation is something that any Time Lord might do at any regeneration, so treating gender as a limiting factor in attraction wouldn't make sense for the Doctor.
No, what has changed is that Fourteen is the sort of person who will directly admit when he finds someone hot while gossiping with his BFF. Not brilliant, or fascinating, or even beautiful, but hot. That's what's new.