You've only got to look at the volume of scamming from Africa to see that what starts as desperation to escape poverty becomes a lucrative business and I'm sure many people in other countries start to realise this and that many westerners are "soft touches".
Unfortunately cases like this are what makes the British immigration system so suspicious of all women from the far east who come here on fiancee and spouse visas. As much as we hate the inconvenience for us they're trying to protect us. Unfortunately this one slipped through the net. Obviously she was a very good liar.