Not much more you can do than explain to them clearly why you think it’s wrong from the perspective of both sides, whilst always reiterating they you will continue to love and support her. You need to explain why this man might be interested in her due to her age, and also that he may have enough experience in life to effectively lie and manipulate without her realising. At best you should get someone she trusts well to also explain this, preferably an adult outside of your household.

You can look into counselling, but only if she is willing.

I would not directly intervene until you feel it could become an unsafe situation. I would also not be seen as promoting the relationship either until you are also clear this person.

No problem, just note shipping times can be higher than other stores. Also be sure to use the EU domain (linsoul.de) otherwise customs duties may be added :)

Check out linsoul if you are in the EU or massdrop if you are in the US.

There are a huge amount of basic, low cost earphone manufacturers. The budget audiophile community can also provide more targeted help if needed, just be sure to include more info like price range, how you plan to use the headphones and what quality you expect, to get more helpful advice.

I’m currently using a €25 set which have almost identical sounds quality to my €200 headphones in many situations.

*Edited because apparently I can’t spell…

I’ve done this with an old pair and works fine. It may be worth noting that I have had a few of these adapter’s fail over time. So if OP takes this solution, I would not recommend permanently fixating the adapter to the headphones (e.g. with super glue)