> telling them “I could be interested in a variety of relationships with you” is so much more indirect than asking “wanna get dinner?”

While you may be correct that his statement wasn't direct, I would say your alternative would be the very definition of "indirect".

Being direct in such situations may not be the best approach, and I suspect that is what you're trying to get at. However, "wanna get dinner?" when you want something more than just dinner is almost a textbook definition of indirect.