I want to focus on "closeted bisexual." Mitchell's father was married to his mother, so how does he count as closeted if he just kept quiet about who else he's sexually attracted to? That's the general practice among married people, not to speak out about your interest in anyone other than your spouse and not to do anything about it. It might be a more poignant case if the man married a woman but only felt attracted to men, but this, we're told, was a bisexual. Presumably, he was attracted to his wife. Where's the closeting in restricting your sex relations to your spouse? It's not as if heterosexuals feel free to speak out and act out about their sexual attraction to others. No one admires these adulterers for "coming out of the closet."
Indeed, chastity in marriage is only really a virtue because you're attracted to others. Of course you are; that's out of your control due to basic biology like pheromones that affect you subconsciously. The virtue is the practice, eventually the habit and finally the character, of keeping faith with your spouse in spite of whatever temptations there are in the world.
To link the discussion with an earlier one, here the virtue is an art that aims at the recognition of and then the perfection of nature. It would be a denial of nature to claim that you simply weren't attracted to anyone else but your spouse; indeed it would be the vice of lying. We use natural reason to understand that the best sort of relationship that such feelings can produce is one of faithful loyalty and duty to one another, and then we use our arts to nurture that thing into its actuality.
Sir Thomas Malory was accused of an affair with a married woman and celebrated both Lancelot and Guinevere as well as Tristram and Isolde. Yet he understood the value of the thing even if he didn't himself always attain it. In the quest for the Grail, only three knights attain success -- and neither of those two, who were the great victors in battles and tournaments. Two of them were virgins, Galahad and Percival. The third was Sir Bors de Ganis (i.e. 'of Wales'), of whom Malory says this:
[F]or all women Sir Bors was a virgin, save for one, that was the daughter of King Brangoris, and on her he gat a child that hight ('was called') Elaine, and save for her Sir Bors was a clean maiden.
One rarely sees the term 'maiden' employed just that way, first aimed at a man, and also one who is almost but not quite a virgin.

