The
clue to the problem of sensitivity when the foreskin is retracted is - that when the foreskin is
not retracted, there is no problem. This means that there is
nothing wrong with the sensitivity - it is what it is. What you then ask is - what does the foreskin do that makes it comfortable? Well, clearly it negates
friction because any drag causes the foreskin to slide over itself rather than moving over the glans itself.
The clue then is friction, and lubrication to avoid it. Friction can be dealt with using the following two-step algorithm:
1} If it is uncomfortable, apply more lubricant - a good "artificial" lubricant sold for the purpose. How you do this is an interesting point - basically you need to squirt a bit inside the lady. Putting it on the penis (or indeed, condom) means that most will be wiped off as you insert it. I leave it to you to figure out exactly
how you get the lubricant in there.

2} If after applying lubricant, it is
still too sensitive, then refer to step 1.
I have to point out - if you say "This seems to occur due to the natural lube pushing my foreskin back", what you
actually mean is that your foreskin is being pushed back because of a
lack of "natural" lubrication. You have two options - get her to make more, or use an "artificial" lubricant.

Paraphimosis? Yeah, it's a concern all right. Best way to avoid it is to
stop reading pro-circ sites! And if your foreskin gets pushed back and it is uncomfortable, well, you just pull it forward again. How easy is that?
{If you do the reading, you will note that you use the "pullover trick" - like taking off a pullover from the bottom, you grab the foreskin on both sides
behind the tight part, and pull
that part over the glans, then just keep pulling until the tight part slips forward again.}