Earlier quoted context omitted.
that only works if you are so careful with your identities that they can't be linked. so that won't help your wife. there certainly are people who want this, but the burden of proof is on you to show that demand is more than hypothetical or anecdotal. this is a niche feature, not a killer app.
I never claimed to have proof that there would be sufficient demand for this. But if I had to prove something, I would start looking at the number of users who use apps that allow you to use multiple twitter, facebook etc. accounts. By the way, my wife already manages different identities by using different services (ie facebook and linkedin).
facebook does not allow multiple accounts. twitter doesn't have that many users.
"niche".