Please, if it’s not too difficult, I know your aversion to second-order halakhic rulings, and even so—do you know of sources on this topic?

What do you mean? If there’s an answer, then the sources are known too, no? Is there some new fashion of gut-based halakhic ruling that I missed?

There is no need at all for sources. The one who needs to bring sources is the person who forbids it. Everything is permitted until it is proven that there is a prohibition involved.

Obviously there is no prohibition on the studying itself. There is a prohibition on lustful thoughts plus looking at beauty (the latter, according to some halakhic decisors, is Torah-level), and from there let each person decide how much he is willing to risk violating prohibitions.

If it is unavoidable and unintended, it is permitted—and here sometimes it’s also not possible to find separate classes at the same level and quality as the mixed ones. As long as they do not intend it, it is permitted—even Torah prohibitions.

Come on, come on, he’ll definitely intend it.
Just say that you’re not really that interested in seriously keeping Jewish law.

Noah, seven mistakes in one go. Your piousness impresses me מאוד, but it’s a shame it comes with ignorance. Go and learn the topic before you scold people here.

And you, as someone who has already learned the topic and therefore already allows himself to scold people—are you saying that even if right now he does not intend it, but it is clear that while walking down the street he will intend to enjoy it, it is still permitted?

Learn the topic and then we’ll talk. It is obvious that you have no idea about it.

I really will learn it and come back here.