You and your wife's phones are almost certainly tied together in multiple databases that adtech companies (especially the quieter tiers below Google/FB themselves) maintain and sell. And then you get re-targeted for ads you or her see, or ads based on things you or her see (retargeting was a really big thing back when I was in the industry, since behavioral prediction wasn't quite living up to the hype - so just re-show stuff you already think is relevant! I'm sure you've seen stuff like "here's thirty other lightbulbs" after you buy one lightbulb on Amazon in the past decade.)

Here's how it worked ~12 years ago: At some point you almost certainly have used the same home internet connection. A cookie associated with some account(s) of hers gets associated with that IP. Same for some account(s) of yours. Find IPs that over small time frames only have a handful of distinct users to filter out coffeeshops and such. Bam, likely family or roommate connection. Some sticky "supercookie" stuff or similar gets set so this can be both resurrected even when cookies expire (through like Etag cache headers or whatever) and then there's a lot of behind-the-scenes ad network offline-cookie-syncing.

One of the companies in that web partners offers ads on FB, another runs ads on Google, she searches and click something on your wife's phone (at this point regardless of network), it gets tied to you too.

It could be more innocuous but tracking same-household, cross-device for retargeting... all that is really old hat at this point.

I intentionally moved my career pretty far from ad-tech in the past decade, but from what I've heard in adjacent convos and such is that the newer developments include some of the newer platforms like smart TVs into all that old cross-device fun, too. Both as data source and ad display destination. A lot of TVs phone home about what you watch, even - like https://clinch.co/clinch-partners-with-samsung-ads/ There's a million ad-tech companies out there, they aren't all just writing real-time-bidding algorithms for traditional display ads.