If it took you 4 yrs to kinda think about marrying this girl...then you probably didn't want to marry her in the first place bro. She didn't leave you cause the guy makes more money she left you because she wanted a change in her life. She will not be with this new guy for long...He is just the "transitional" comfort zone guy..Just count your blessings that you don't have any children with this girl (I'm assuming) and move on.
P.S. The perfect girl does not exsist! Everyone has issues...Just find someone with issues you can live with.. No matter how beautiful and perfect a woman may "seem" to be...There is a guy out there some where that is "Sick of her shit"
bobv