Just wonder

I find a lady whom I am really interested in on Lavalife and I am going to purchase her IM address. But I recall one friend 's real experience: he keeps contacting with a girl in a dating site via email for a long time. Later, he intended to buy the lady's IM address. But the girl never reply him by IM as if she don't know the man. So, he has to write email to get contact with the girl again. Yes, maybe the IM address is not true. But what if it's Her IM? So who's the lady writing email to him?