You’re both signing up and aren’t one singular entity. She might be the one actually using the app and whatever line of credit but you’re still signing up with the bank. They need a way to do 2FA for you and not just her. If you divorce, how are they going to do 2FA when you’re separated? If it was her phone number then she could imitate you and get more credit or do whatever.
Etc. etc.
Genuinely no idea why you’re not considering this.
Etc. etc.
Genuinely no idea why you’re not considering this.