They won't last and she knows it herself, even look what she said in this interview. She showed zero confidence in him, saying she doesn't look at his phone as she doesn't want to see anything she's not meant to.
She then said they were getting married, but then mentioned even if they don't get married and don't last he will still be a great dad.
It's not really the way a normal couple speaks, she probably knows he's cheating on her and it's only a matter of time until it blows up in the media and they are done.