I disagree with first hint Doctor has been getting into trouble, because before Barbara and Ian's first adventure, Susan said in the Unearthly Child Earth 1960s was her favorite place, that implies she's had other adventures to compare with.
I don't see any problem with a straight man finding Barbara Attractive, no reason to declare your possible insanity over it.
One Day I hope to be the Man my Cat thinks I am
Where are we going? And why are we in this Handbasket?