I have an aunt who tells me her ipad is broken every time she sees me. She's not dumb, but I do think the ipad actively does a lot to prevent her from understanding what she's doing. Anyway, there is a maximum number of open tabs in Safari and once her device hits that number it's "broken." The fix is to just close them all. I've explained what I'm doing and why. I've demonstrated the concept of tabs to her on a desktop. Doesn't matter. She's going to forget before it becomes an issue again, so three or four times a year, I just close all her tabs while complaining that I had to use iOS.
Mobile OSes hide a lot of complexity from end users. People don't HAVE to do file management on them and often don't know why they're getting notifications or what they're supposed to do with them. At the same time, no one was born knowing how to use any of this stuff and a lot of people don't actually want to learn, either.
Eset isn't going to fix your girlfriend's problem. Paying attention to when things want notification, location, call or contacts access will help her a lot, but you that's something that has to be patiently explained. I like to set people up with ad blocking everywhere I can and I like to explain why app permissions are a big deal, but at the end of the day, people are going to do what they want on their devices and if that means installing 47 Bible apps that each want to show lock screen ads, that's just how they're going to live.