WIBTA if I were to interfere with this relationship

I am aware of a grooming situation online. The 2 parties involved are a girl (14), and a guy (21). The problem is, I know both parties.

Both parties are aware of their ages, but do not care. They are quote "in love" and convinced that there is nothing wrong. Their love isn't "innocent" either.

Me and the other ppl aware of the situation have both brought up the problems, with what is happening between the 2, and they simply ignore it. It's quote: "None of your business"

Another thing to put into light is that the guy is very mentally immature, so I am not sure if he is aware of how bad the situation that he has put himself in.

The thing is the guy has a bright future ahead of him, and if this gets out it is ruined. I simply cannot bring myself to ruin his life.

The girl on the other hand, if she finds out that I was involved to break them up, or sabotage the 2, she would cut off everyone in the friend group, including the ppl that are not aware.

What is the best course of action in this situation?