What the OP described didn't sound like a guy being "controlled" by a woman, unless being decent and respectful to women is being controlled by them. Chivalry is sometimes used to refer to putting women up on a pedestal, opening doors for them and deferring to them in certain ritualized contexts, but it's really an entrapment in patriarchal settings, with the men the ones calling the shots with the implication that women are fragile flowers who can't do things for themselves (or must be jealously guarded from other men).
I'm not sure what you mean by "entrapment in a patriarchal settings." I'll have to give that some thought.
I don't think anyone is saying that men being decent and respectful to women equals being controlled by women. The OP wrote, "at what point does the trope become off-putting if said knight tries too hard for a lady and seems whipped?"
The suggestion I'm reading there is that the knight in question is in service to the woman. He is effectively her servant. "Bring me my coat," she says. "Fetch my stool, light a candle, it's dark in here, cut some firewood, saddle my horse, slay my naysayer, purchase me this trinket..." The worry I believe the OP suggested is that the knight might stray too far into service under the guise of being respectful and accommodating.
I think of it somewhat like Westley in The Princess Bride. He is a serving boy at the beginning of the story. Young and naive in love. No matter what Buttercup needs, he responds, "As you wish." This is not the response of a man in a reciprocal relationship. This is the response of a "whipped" boy, a servant in service, just as young Westley is in service to Buttercup. He doesn't respond to her with honesty. He doesn't let her know what he wants or how he feels; instead, he hides behind a persona that exists solely to grant her wishes. For Westley to grow up, to become a man and find his own agency, he had to leave and develop himself.
Westley returns, and he is now the Dread Pirate Roberts. Left a boy and returned a man, he no longer treats Buttercup as his better. Rather, he challenges her and he holds her to standards. The reason is because he now knows himself, and that knowledge of himself allows him to be true to Buttercup. He no longer lies to her about his wants and needs. It's no longer him in the background letting things be as she wishes. Still, Westley accepts it as his duty to protect her, just as he would presumably protect anyone he loved, and just as Buttercup accepts it as her duty to protect him. This is a reciprocal relationship between adults, absent persona.
That is an example of a relationship growing in a healthy manner. Unfortunately, it doesn't always work that way. Sometimes the relationship lingers in an unhealthy hell, with each side attempting to dominate the other. This power struggle erodes trust, creates chaos, and leaves emotional scars. Maybe the "whipped" boy never grew up and instead learned to resent her wishes.
Take the Leonard Cohen song "I'm Your Man" as an example. It begins by saying, "If you want a lover, I'll do anything you ask me to." The song continues by making powerful pledges, saying, "And if you want another kind of love I'll wear a mask for you. If you want a partner, take my hand, or if you want to strike me down in anger, here I stand. I'm your man."
Imagine that. This man is giving himself wholly fully completely. Or so he says, and I have no doubt that he actually means it when he says it. But as the song continues, we learn more about the way of things. "Ah, the moon's too bright, the chain's too tight, the beast won't go to sleep." So here the man is struggling. How can he be who he isn't? How can he deny his own wants and his own needs? The song then says, "I've been running through these promises to you that I made and could not keep."
He meant those things when he said them. He was whipped. He was in service. He was a child in love, and he had no idea how to be honest with himself. As time progressed, he learned. He learned he could not be a servant to her needs alone. The beast would not go to sleep, it needed more chain, and he made of himself a liar.
The rest of the song is just as fascinating in my opinion. It's like he's stuck in this pattern of behavior that he can't control. He says, "Ah, but a man never got a woman back by begging on his knees." And how true is that? Very powerful insight there. He knows he can't save his relationship by continuing to be a slave, but oh if he could he would as he goes on to say, "Or I'd crawl to you baby and I'd fall at your feet and I'd howl at your beauty like a dog in heat and I'd claw at your heart and I'd tear at your sheet, I'd say please (please), I'm your man."