I wouldn't say that my partner "doesn't care", but they take a much more pragmatic view than I which results in more exposure. In general, we do the following:

1. To a first approximation, they decide what apps and services they use. It's not a monarchy. They'll ask for feedback when comparison shopping, but often the answer is "every dominant ecosystem in this space is terrible, the privacy respecting options don't meet your requirements, this option is 5% worse and this one is 5% better... glhf".
2. For social media accounts that share posts about our nuclear family, we come to broad consensus on the privacy settings and practices. There's give and take here, but I make space to use dominant sharing apps and they make space to limit our collective exposure within reason. If I have a desire to "harden" the privacy settings on a service, it's on me to put in the effort to craft the proposed settings changes and get their buy in on the implications.
3. I have many fewer privacy raiding accounts than they do. I both benefit from transitive access to the junk they sign up for, and pay a cost in my own privacy by association. This just is what it is. The market for partners that align with my own views perfectly is basically zero though, and honestly I probably wouldn't put up with my shit even if I could find one.
4. If I can self-host a competitive option for a use-case that I'm happier with... they'll give it the old college try. But it has to actually be competitive or they'll fail out of the system and fall back to whatever works for them. If we can figure out what's not working we'll sometimes iterate together, but sometimes it's just not good enough and we go back to something I like worse.

It's basically like navigating any other conflict in values. You each have to articulate what your goals are, and make meaningful compromise on how to achieve something that preserves the essentials on both sides. As a privacy outlier, sometimes one also needs to be able to hear "I want to do normal shit and not feel bad about it" and accept it. But if we do want to reach for outlier privacy practices in some specific area, it's on us to break that desire down into actionable steps in realistic directions at a sustainable pace and to not ignore the impacts to our partners of the various tradeoffs we're proposing. Privacy is often uncomfortable and we need to acknowledge the totality of what we're asking for when we ask our partners to accommodate our goals there.