I never said they didn't have any idea what love was; there just wasn't this connection between love and marriage back then that you see today. Love was seen as a separate thing, with the institution of marriage often being portrayed as an obstacle to love in literature. In the old stories, love either lead ultimately to death, or only triumphed because both love and marriage obligations were able to be fulfilled simultaneously.
The fact that feudal nobility, who habitually practiced marriage for political reasons, and were also the patrons of the arts through the middle ages, saw marriage as often an obstacle to love, does not remotely prove the premise that this was how society in general treated marriage.
You're going to have to do a lot better than that to try to prove your point.
I’m not referring to the concept of Yandere specifically though? I’m referring more to a broader concept.
Men have historically been expected to pursue women. Which is fine, that works.
My point is a great many men would be absolutely delighted if women pursued them.
This doesn’t happen in reality. Whether your good with women or not. So it’s a male fantasy.
I think there's two elements to what you're talking about here.
First, is that a lot of men wonder 'would she still love me if I stopped being the primary initiator in the relationship?'
Second, is that in the modern era that increasingly gives women more social and legal power over men, it's not
safe for men to try to pursue women a lot of the time, and the woman pursuing the man gets around this.
Beyond all of that though, as others have mentioned there's a certain raw appeal for either sex, to someone who is 'into you' to a downright obsessive level. That's a huge part of what Twilight centered around, for example.
Interestingly enough, a male love interest who is
violently possessive of a woman, if she returns his interest, is
much more likely to be seen as a good thing than a bad thing. Even in Weeb/Otaku communities, guys who consider violent Yanderes 'best girl' are subject to derision for that. Twilight, on the other hand, and the even more messed up 50 Shades of Gray fanfiction spinoff, were
insanely highly-selling books, 50 Shades selling over a hundred million copies.
It's an interesting perspective difference on what's viewed as socially acceptable.