John seems to have mental scripts that he relies on to get through certain situations ("oh, this calls for 'generic flirtation #2'... lemme see if I can find a picnic basket") but there's a kind of disconnect that I think Flanigan put there (and that the writers couldn't do anything about). And the great thing about John's team is that he doesn't need to use his scripts with them: they don't matchmake or ask him about his sexual past or for advice, and they respect and love him for who he is.

You've managed to hit the vibes I get from John in a way that was 100000x more coherent than what I was managing to say. And this rings very true for a lot of the ace folk out there (myself included) because this is what society teaches. If it's not working, just keep going until it clicks. What I see in Sheppard through the series are Not-Quite romances with dubious chemistry that are broken up with by long periods where romance isn't even vaguely hinted at, where Sheppard manages to hold himself so stiffly people don't even try to touch him.