Contradiction to your statement "guys leave their wives" I know a case where a girl used this way to get her bf to Canada.
A story goes like this..Oscar wining story
A below average looking guy got married to a very good looking girl and they stayed together for almost 2 years, after which that "Canadian PR holder" girl came back to India, demanded a divorce for no obvious reason and later that guy ( the poor husband) found out that she had a bf back home and she was in contact with him through out those 2 years.
Now the the worst part of the story - that guy had sacrificed his own study ( did a labor job instead) and spent thousands of dollars after his wife's graduate full time course without asking her to help financially towards her own study fees. She finished her study, got very nice job which was paying much better then her husband and then left him only to get her bf from India.
I do not know what happened after that but I feel sorry for that guy. He is my Bro's friend.
So moral of the story
sirf ladke hii nahi, ladkiyan bhi bewafaa hoti hai