"He is very in love" is not particularly good English ("very much" would be correct). It seems to me like "He is very loving" or "He is very romantic" should also be acceptable answers here.
Well, "vraiment" does mean "very/really", and Duolingo is all about true translation, not necessarily loosely correct translations that account for colloquialisms. That's the root, colloquialism.Besides, "very much" would be "tres" in this sense...
Yes, I see what you're saying...but it doesn't seem right to encourage literal translations at the expense of proper grammar in the second language. In this context, it's understandable, I guess, and your point about using "trés" for that instead is well taken. "He is really in love" would be ok, but I don't know if they'd accept that.
I imagine it's been updated since this discussion, but the default answer now seems to be "he is really in love," which doesn't sound weird to me in English.
I translated it very literally (alas) as "He is really amorous" and I got marked wrong and I totally accept that, but what would "He is really amorous" in french be?
The French is "oh là là", and it's either an expression of surprise, or sympathy and concern. It really has nothing inherently to do with sexuality or physical attraction.