I want to say up front that after reading the Wikipedia article for romantic attraction I was confused and thought it was saying that romantic love was invented in the middle ages and romantic attraction was just a strong emotional bond + societal norms attached until I asked some of my friends and they confirmed love wasn't invented in the middle ages for me and told me love stories have been found in early stories. So I know where you are at with the confusion.
On that note, to answer your question, no, aromanticism was not the norm. Not at all. In societies where people have arranged marriages, you are expected to learn to love the person you marry. In Shakespeare's time, it was considered unhealthy for a woman to marry without loving her husband and arranged marriages would be arranged by having the eligible bachelor woo the woman over time because it was thought if she was unhappy, she would be unhealthy. If you married someone and didn't learn to love them and your partner was not abusive, mentally ill, or completely financially irresponsible then you should try harder and stick through it because you probably already have children and dowrys need to be returned if marriages fall apart. Beauty and the beast originally started out as something to ease young girls into the idea of marrying a stranger. This isn't always the case, as some arranged marriages are heirachial and polygamous, but monogamous ones generally expect love to develop.
As for PDA, Pride and Prejudice, Pictures of Victorian couples that aren't actually just staying still and frowning because the camera needs to be set for 10 minutes long (PDA), any source of media from ye olden days where someone doesn't like the person they are being forced to marry, etc. is my answer.
> "but it seems that most historical societies were oriented around the idea that having a partner was more about procreation, creating bonds between families, and fulfilling sexual needs; not about romance. Most of the romantic overtures that I have seen from this period actually seem to be pretty demiromantic, partners grew deep emotional bonds and then fell in love...they were not in love from the start."
Yes about the former but no for the latter. It was incredibly common for people to want to marry other people than those they were supposed to marry, and lots of tragic/depressive literature from the time was based on this. People had crushes on people they barely met. Demiromantic is a uniquely terrible description of the norm of forced marriages in any society considering the atmosphere of sexism, ableism, homophobia, and more than required people to learn to love whoever they were married off to for the sake of their family unless they had certain socially acceptable reasons to not love them. It wasn't "falling in love after forming an emotional bond" so much as "falling in love JUST for marriage, and just for marriage for practical reasons first, and tough shit if you don't like that*. Demiromantic is only a concept that makes sense in a society that believes that the inklings of any romantic attraction can and should come before you truly know someone and it is, therefore, weird to only fall in love with people you have a strong emotional bond to and does not belong in discussions of general cultures where arranged marriages are normal.
>spreading into other cultures
This is racist. Granted I'm being a bit hypocritical, considering my first paragraph, but I will say the Wikipedia article only mentioned the west and while I should not have forgotten the rest of the world in my panicked questioning, you didn't forget. The Philippines has a creation story where a God had an argument with his wife (a goddess) and she left, and in trying to find her/get her back he took basically dirt and clouds and made the stars, oceans, mountains, forests, and everything else. China used to heavily romanticise an emporer that cut his robe rather than wake his sleeping (male) lover. There is absolutely no reason to think that after the Renaissance and after colonialism/mercantilism/better forms of communication the west spread its new idea of falling in love before you were married/marrying for love to the rest of the world.
> but it would be nice for people to at least acknowledge that romance has not always been as important to society as it is today
They do. It is common knowledge that people used to generally marry for social status, money, and practical reasons. Every discussion about arranged marriage either assumes this or will blatantly state this and it is well known that in certain important periods of western history you did not marry without permission.
Edit: basically what @awra and @aro_elise said.