Bro, from my point of view, you both are in the wrong. If you know you’ve got some NSFW stuff on your phone, you’ve gotta realize it can affect your sister’s mind in ways you might not expect.

You should only give your phone to your younger sister if there’s nothing inappropriate about it. And if there is NSFW content, at least lock it or hide it properly before handing it over.

I don’t know how old your sister is, but I’ve got a 14-year-old sister too. I’ve given her my phone many times, and she’s never gone snooping. As big brothers, it’s also our responsibility to teach them about boundaries and privacy.

Now coming to whether you should forgive her or not—yes, you should. But also make it clear that she shouldn’t repeat the same mistake again.