Are you saying that we do not respond in the same way as many mammals? Are you denying that some women do get sexually stimulated by being disciplined?
I think most of us are aware that there are some people who eroticize being spanked or spanking someone else. It might be the most common 'kinky' thing there is. It shows up in jokes or comments in movies, occasionally.
I read about 'Christian Domestic Discipline' many years on a website. So I looked it up online. I saw there were comments from women who were very much in favor of it, and some of the men got involved because their wives instigated it.
There are women who eroticize the idea of their man spanking them, disciplining them, etc. They associate it with masculinity, strength, or whatever.
If a couple have some spanking going on in their bedroom as some kind of sexual (in their mind) activity, is that sinful? Well, if no one is __really hurting___ the other, then I don't really have a strong opinion on that myself. Is it loving? Maybe for them it is sex. It can get into more of a lifestyle thing, where a woman finds a man who is 'in charge' by spanking her if she doesn't live up to his standards is an erotic thing, or something like that. At some point it gets weird to me. I am speaking of my own impressions and feelings on the matter. People can do all kinds of stuff in their bedrooms that might embarrass them if they told others, from lingerie they wear, or rubber suits, or dressing up like a nurse or Batman, or whatever it is people do. Most people probably do little of this, except lingerie which might be kind of popular.
Bedroom play in marriage is different from what most of us think of when we read 'wife beating.'
The Bible does not directly mention wife beating that I know of. But since we are talking about hitting someone, why not consider it form the perspective of what the Old Testament specifically authorized. It allowed disciplining a slave. On the other hand, the New Testament forbade threatening a slave. Beating is more extreme than threatening, so why would beating be allowed for Christians in that type of arrangement. The Proverbs also talk about physical discipline of children. Where did the Old Testament authorize physical discipline of wives.
I'm not a liberal when it comes to gender issues either. I think our society is probably less patriarchal than would be optimal for a society. I do not agree with the underlying assumption that I see from a lot of US evangelicals that God's spiritual plan is to ultimately lead us to certain western values that are not taught in scripture. For example, I do not think it is sinful for the state to allow businesses to require a husband's approval of a wife's financial transaction. I do not see any reason in scripture to think that it is sinful for the state not to allow women the right to vote, or men for that matter. I do not see a mandate for democracy or republics in scripture, either. God gave a number of laws that we might consider patriarchal.
But none of them that I am aware of allow or regulate husbands hitting their wives.