So I'm looking to tag post #633680, and it seems to be impossible to tell if the wolf just finished having sex with another character(s) or fellating himself. I've noticed a few other examples like this around the site. How should I tag this situation?

I think TWYS would favor auto-fellatio and solo over any tag implying someone else is there, even if it does seem like he's looking at someone else.

Although it doesn't matter technically speaking, in solo posts after_sex tends to be used more for cum dripping out of an orifice (anus, pussy, etc.) than anything, if the solo is just a dripping penis it tends to end up with ends up with after_masturbation.

For pictures like that I'd favor masturbation as it's much easier to explain with masturbation than sex, and using masturbation doesn't require us to make assumptions (e.g., unseen characters).

I just use after_orgasm in almost all cases myself.