I agree, the whole concept of what "technically" constitutes adding a number to your sex-partner list can be a bit of a mindfuck for women. Many don't count having sex with someone unless there was penile penetration... This allows one to act like a slut, while still retaining an image of moral virtue in her own mind's eye.
I know some girls like this as well... and yeah, it doesn't make a lot of sense (except to Lewinsky/Clinton enthusiasts).
In the early stages of my sex life, I did this with a few guys. Mainly they were guys that I wasn't sure I wanted to sleep with and so oral somehow seemed like a functional compromise of hooking up with someone but not having to acknowledge it to myself formally.
My number of "oral only" partners is extremely low, however. For me, once I get naked, I'm pretty much committed to the entire sexual menu... it doesn't happen in stages. I don't see the point of limiting the pleasure, and I don't really subscribe to the psychological hang-up of it anymore. Besides, I don't typically have the kind of self-control required to re-negotiate along the way once the clothes come off...
I've had a few onenight stands back in the day, but I have to be in a serious relationship before I'll suck a guy off.
I've given plenty of throwaway, unemotional sex in both oral and vaginal- and anal actually lol. I've never thought about it this way. My thing is always that I don't kiss unless I really like a guy, but I see your point that oral is more personal than vaginal sex. It feels like more of a favor than vaginal sex, since at least with real fucking, we're both getting something equal out of it. If it's simply a sportfuck, or a one night stand, I"m far more likely to have vaginal sex than oral sex, but often both happens.
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double post- damn iphone!