Do you think there should be a law for this?

I just finished watching a documentary about dark internet affair. An 18 year old girl starts to talk to an 18 year old boy (she thought he was an 18 year old boy, but in reality he was a middle aged man) in a chatroom and they had a long drawn out affair, well the 18 year old girl met a real 18 year old boy in the same chatroom and so now there is a love triangle going. (she eventually found out that the man was not an 18 year old boy, but kept the affair going anyways)

The middle aged man is now getting jealous and threatens to hurt the 18 year old boy and eventually ends up killing him. Now come to find out it wasn’t an 18 year old girl that was carrying on this love triangle but it was the mother of the 18 year old girl that lead this middle aged man on as well as this 18 year old boy.

The man was charged with murder and convicted of course, but the mother was not charged with anything. It was a wicked tale of lies and deceit and unfortunately it was the one that was telling the truth that got it in the end.

So my question is should there be a law of some sort condemning what the mother had done? Or is it just the person who “pulls the trigger?” Or did she start a deadly fantasy online that ultimately led to young human beings death? Should she be sitting in jail with the “trigger puller?”