tmnt comic Beautiful Heart 35

At least Casey was honest with him. Even if Casey's not gay I know he wouldn't be a homophobe (though I'm sure he might not be comfortable with pdas between dudes) and I know he would never stop being friends with the turtles because of something like that. You do a good job of portraying him.
  I also agree that while Don might be the best behaved on the team, he's also not one to go spilling secrets or tattling to Leo about everything his bro's do. That's why they are comfortable talking to Don... he doesn't judge or give unwanted advice or lectures, he just listens... and he keeps secrets- doctor/patient confidentiality and all that.
I bet Donnie's really hurting now though.