Interesting topic!
Simultaneously on an other topic, we are debating, maybe its better wife's don't kite all together, and here we are thinking how to share the wonderful feeling of foiling with our family.
While I taught my wife to kite @45 I'm not sure foiling is a good idea for my her to get into...
Don't take me wrong, I'm confident she is more than capable to actually learn the technique required, my hesitation comes from her dealing with issues involved with crashing, foil in lines, long swim, sharp objects coming at you with speed etc. and generally surviving the first 3 hours
I believe (like getting wife to kite) the answer is very much individual, you need to know how your partner deal's with situations where she needs to stay focust, see things in advance and be able to think clear when needed.
Same as kiting with a TT, only more advanced.
I taught my son to kite when he was 12 and to foil at 14, for the first 6-12 months I was "hovering " up wind from him, in case we have a situation and we did...from kite in slow death loop with foil in between line's to lost board. I did that because I knew he will get it, but was young so its a learning phase, with my wife its different.
Nothing makes me happier, but to share a session with my Family, however I think the foil for at least until she has super confident kite control and a perfect place to learn (!) it's not for her...
cheers