hey, this problem is'nt about me, but a friend.

Recently a good friend of mine has started seeing a 25 year male, while she is only 16. Now i find this a little worrying since this guy has in the past had a sexual relationship with a minor(15yo) and i'm very worried about my friend, I have a horrible feeling that she will get hurt by this scum bag, as he will either once again find a younger model just use her for sex and leave her when he bets bored, any idea's on wot i should do????

and Yees i know it's really none of my business who she see's but,