She is English
Married an American
Immigrated
Broke up
For some reason she assumed he had divorced her as he had remarried so she married a foreigner.
Petitioned him and it all came out
Having said that and here we go back to Lagos amazing how many cases where someone has come as a Tourist or Student, arranged for a Lawyer in the home country to divorce spouse and it has not been done properly and USCIS find out, so they have to get divorced properly and marry.