Doing it in a cardboard box could be cute. At least have to try that, could be romantic.
Never the less. You think that a man should provide for his woman. The concept we all are really looking for is equality.
Let's pretend you are a typical alpha male. You spend just about a fortune on your woman and then what? Sooner or later your will run short of cash. Then someone else will overtake your investments by simply opening up a larger wallet that yours just because she is like a freelance contractor who serve whoever she wants, for money of course.
What if she could spend just as much as you do on everything, together with you? As long as women can be bought, they won't really be free or loved for who they really are and men will hand them money for nothing. Why on earth should you work for her? Is a woman really free if she always is on some mans pay role?
Does it matter if things don't make sense in erotics? It's supposed to be art or at least main stream. Oh and this group thingie with people helping each other to have intercourse, taking turn, giving support or just watching, all humans do that, right? (Little ironic here, but if we were free of all social, economical and juridical matters orgies would be more common, like everywhere.)