Your reaction to people you've asked for opinions from, giving those opinions, is bizarre. This is a reverse - I reckon you're the female friend, in this scenario.
The following part of your op,
'To me, whether she's going through a hard time or not, it's still his choice to see her so frequently isn't it? It's not like he can't say no?'
Followed by this response to a poster, is telling: 'I didn't ask anyone if they thought he was having an affair at all. I asked if something was normal for a friendship and it's spiraled from there.'
You're asking something, and for some reason. It's not quite clear from what you're posting, but it's giving some hints.
If, as the partner of this man, you are singing his praises in all other ways, & shutting down opinions it could be signs of an affair, then why are you asking if his behaviour is normal? What exactly is the problem, if you don't think it's a possible affair (whether physical or emotional) scenario?
I've never said 'reverse' before. But it's screaming at me on this thread, with the defensiveness when your original post came across in such a manner that you did indeed, suspect something.
I reckon you're the 'female friend', and have become aware he's telling his partner the excuse of you've been going through a hard time for three years, and actually asking 'it's still his choice to see her so frequently isn't it? It's not like he can't say no' ie- he must really like me, mustn't he, because he could say 'no'.
I honestly can't fathom any other reason for your bizarre reactions to posters offering their opinions as you've asked. You either suspect somethings up, ie an affair or you don't, the latter case makes no sense for you to create a thread..
And yeah, you've been right snippy to a fair few on this thread.