Thanks for the detailed update, man. It's really hot to read your progress after 20+ years together. The fact that she's slowly opening up while staying true to her own boundaries shows how strong your communication and your love for each other really is.
One thing that strikes me when I look at the photo (especially her breasts) is that she seems to have had breast reduction surgery at some point (or something). One of my ex had a similar surgery and she was having mixed feelings about her body. She never told me directly but she did not like her body much.
I get the impression that your wife's biggest internal block isn't really the idea of another man... it's that she doesn't love her own body enough yet. She's reserved and proper, as you said, and that often comes with deep self-consciousness. Even though she enjoys the massage and is now open to being filmed while you fuck her, she's still protecting herself a lot (thong on, no direct touching, masks for privacy, etc.).
My suggestion for the next several months (while you prepare for her birthday and this new experience):
Instead of rushing straight to the "filming with a guy watching/jerking" step, put a big part of your energy into rebuilding her self-confidence and her love for her own body first. Make her feel incredibly desired and beautiful as she is right now. Compliment her breasts specifically in a loving, lustful way — tell her how much you love their shape, how they feel in your hands, how sexy they look when they're oiled and moving, etc. Overdo the praise in a genuine way (or whatever part of her body she doesn't like much).
The more she starts loving her own body and feeling sexy in it, the less she'll need to hide behind "this is just for your fantasy" justifications. She'll become more comfortable being seen and admired.
Practical ideas:
- Encourage her (little by little) to dress sexier in daily life and when you go out — tighter tops, nicer lingerie, outfits that show a bit more cleavage. Always frame it as "you look so fucking hot like this, it drives me crazy."
- Take lots of private photos and videos of her just for the two of you, and show her how much you jerk off to them.
- When the third guy eventually watches you fuck her, she'll feel much prouder and more turned on if she already feels good in her skin.
You've already done an amazing job with patience and communication. If you now actively work on making her fall in love with her own body again, I think the rest (including going further in the future) will flow much more naturally and with less discomfort for her.
She's lucky to have a husband who wants her pleasure so much. Keep us updated!