I knew several women, mostly from Eastern Europe who married US men and divorced them right after they got their green card. They admitted that they are just waiting to get the green card, and they married just for that purpose.
Even worse, they married US men and stayed in marriage. While taking husband’s money, they are enjoying sex outside the marriage.
Warning for US men (and women too!) - be careful about getting involved with foreign women (men)!
Most of them are not after you, but after that green card!
One good point here is that the initial green card is only good for 2 years. Then you can get the 10 year one, and eventually the permanent green card, and then after a while you qualify to apply for citizenship.
So, if she bolts TOO soon, she could be making herself an “illegal”.