hobbying or otherwise, but there is one gal who wants me to wear a wedding ring now (Even though I'm divorced.), because it turns her on.

Oh well, the things we do for love.

..... depending on how soon you take it off just before the session I can still see the ring's "tan line". lol
TBH unless he's worried about her stealing it or feel some kind of "guilt" he should wear it.

. . .  sometimes I forget. I was told once by a provider that she was more comfortable with married men because single men not only would ask her out, but also expect her to say yes and would be upset or hurt when she said no. I am sure that some married men can be obsessive as well. I will only speak for myself in saying that it is all for the best to not let this hobby run into our personal lives.

I squirm when I notice people taking off their ring (sometimes it appears, sometimes it doesn't -OR- there is a tan line or indention there) because it makes me consider how many times I've taken off jewelry for whatever social (or sexual usually lol) reason and have left it/lost it.

Who wants to go through trying to explain how or why they lost their ring?

Just keep it on.  We know and we don't care.
I only used to look at it when considering who I wanted to sleep with off the clock lol.