Wow. Just wow.
Sadly, I know of a couple where the woman used her green card and its' expiration date to get married.
She was dating a guy I was friends with since childhood. I remember telling him that it was imho, risky to be dating a non-naturalized citizen like that. The girl he was dating was an au pair and I honestly didn't like her. Then suddenly she announces she has to go back to her homeland, that she has applied for an extention or whatever she could do to extend her time here, but was denied. Then she cried and cried to him, then suddenly broke up with our friend saying "you need to love an American woman who can be with you forever because I cannot give that to you."
She played on his emotions so well, he called me up and asked me to help plan their wedding in two weeks' time.

He had a good job, was a nice guy, and she was imho money hungry too. They got married and are still married 13 years later and have one child. She never worked one day in her life (his w). Within 3 years she went from looking mousy to becoming a bleached out (and when a blonde like me tells you this it's something) burned out platinum blonde with fake stripper b**bs.
they're still married, but I still believe she will leave him or cheat.
One of our other friends did same thing. WAs bff of the guy who married green card girl. His w suddenly enrolled in college, was stepmom to his twins when they were young, and then just worked and worked and became a cpa. This woman was also from Eastern Europe.
Six months after she earned her cpa certification she divorced our other male friend and was definitely cheating on him. She used our friend to 1)become a us citizen and 2) used him to pay for her free college education. Now she's married an old but rich dude and spends money like water. That was her goal and she got it.
Scumbags.