Honestly, it is not an entirely altruistic gesture. She'd do it for me.

Same with lingerie shopping, if you're embarrassed doing that, then you are missing out on some quality post-purchase times.

Quick story, to show I wasn't always so good. A female relative was in an urgent need of some tampons (circa 1994). Sex education was split at my school for the deep dive (sorry) period talk. The boys, we did something else. So although we knew it happened once per month, we didn't know a lot else. So I trundled to the shop, full of embarrassment (like they'd think they were for me or something) and found the display, and noticed a "giant" 36 pack of tampons. I purchased and proudly went home. I assumed I'd bought a 3yr supply, and they'd be elated. They weren't, and I then got a bit of a lesson.

I've improved since then.