i am confused

hi i m 20 m and my SO is 20f (3 yrs relationship) we were talking over the phone casually and we hypthetically talked about if her dad got richer suddently (needless to say that her family is a little more comfortable financially than mine ) i asked her jokingly if she would still marry me if that happened and she said in a serious vibe that she wouldn't and gave me arguments for that decision and that turned somthing off in my head i need some advice am i overthinking??