Some civvies are a bit touchy when it comes to sex, most likey from lack of confidence. Its just part of the relationship shit you have to put up with and work on.
I've found even with women who are gagging for the sex that there's always some kind of contention with sex - like they know you want it more so even if they want sex too they feel they are doing you a favour, that it's not a mutual thing.
The going Dutch thing - my experience is that most often they go dutch or pay the first time - to make the point, and after that its' me. They want equality but can't get that stereotype out their head. Even fuck buddies - nothing quite as fun as getting that £50 curry sprung on you from a girl you didn't really want to go out with anyway cos she's not your girlfriend, she feigns annoyance that you would suggest such a thing, but that's clearly how she sees things.
Sure you can't compare relationship sex to WG sex and both do have their own merits but even forgetting any financial aspects I find with civvy girls 90% of the time there is an emotional neediness (or sometimes just plain batshit mentalness) that is way too expensive IMO.