This was ramune's reaction to her oath line after he ringed her as he apparently didn't know about her 180 degree turn that she collars the shikkan due to trust issues and/or sadism.
This is what he would have done in response if given the choice I suppose.
Not gonna lie, I'd be pissed as well if I wasted a ring on a fetish I'm not into. That being said, you'd think he'd spend a moment to read the voice lines before going for the oath. At least, that's what I do.
I think this is Ramune's reaction to finding out Chapayev is into BDSM after marriage. Her pledge line had her put on a collar on you.
I can kinda understand why she might have that fetish, she is currently the only Northerner who's mastered her mechanical beast rigging to the point of unchaining it's jaws. so her being into restraints sounds about right.
This is kinda of a... fucked reaction to realizing that your kinks don't align. Like damn, are you so insecure that some chains and a collar make you hit a person?