u/Busy-Remote-820

Scenario: I work for a high end business in there head office, I've become close friends with Kim from the accounting department. We go on lunch, we hang out at weekends, we connect.... Something is bubbling underneath, an energy, a sexual tension. Me with my average looks but notable charm, her with her blondish hair, above average chest, incredible legs and eagerness to please people....could it be that we see more in each other than we first thought... She's got a husband though...head of security at a local club that has proven popular with a range of celebrities... The flirting might ramp up a level....then where does it lead...do I take my chances....maybe she takes hers...where does it lead?! Do we sleep together and potentially ruin her marriage or do we leave it at casual flirting...

Wasn't sure what to call this but it might well be suitable! Every now and then, the gf and I have anal sex. When she's on top, it's fine she lowers herself onto me and it's all good.

When we do it with me taking her from behind, it's suddenly a struggle. For some reason as I attempt to enter her, I start to feel like I'm burning up. I get a little shaky and a couple of times, felt like I'm gonna pass out. This only happens with anal this way, not when we have vagnial sex in this position.

Any tips or ideas?!?!