My girlfriend back in high-school got me used to my own cum. She started by teasing me, then putting some on her fingers and into my mouth. That progressed into a snowball and eventually, into me going down on her after we'd fuck. In the months/years we were together, I became totally comfortable with cum. I'd thought that most girls would have been horrified at all of this - but instead, my gf was thrilled and would love to watch me jerk-off and then share my cum with me.
Surprisingly, I later learned that most, if not all, women are impressed, happy and even ecstatic that guys are okay with their cum (or from another guy). In the many girlfriends and ex-wife in my history before Sue, all were really receptive to my going down on them after we'd fuck or to my not fearing kissing her after they'd suck me off. Confirming my experience with my high-school girlfriend - all of these women also thoroughly enjoyed watching me jerk-off.
Since our dating days, I have ALWAYS gone down on Sue after we'd have sex. From the first dates, she had always loved that she wouldn't need to run off to the bathroom to clean up after we'd have sex. She wasn't so vocal about it, I suspect she felt reluctant to ask me for it, but she would ALWAYS welcome me to do so and soon learned that I enjoyed it when she would bear-down and force more of my cum out.
Now, since she's begun seeing other men, it's become something that brings us closer together when she comes home - a way of sharing what she's done with me and allowing us both to enjoy her sexual activity for a second time.
As a cuckold, I would even say that I feel obligated to do this - to me, it is perhaps one of the ultimate ways of enjoying this lifestyle.