There's this manga that's like riman gambler mouse. Except without all the gambling. It was like this guy saw some woman or imagined her and he became obsessed with her. Before that he was straight laced. Then he has some other girl chasing him and like an arranged marriage to some girl that went to an all girls college.

Its sounds a little like Golden Boy but im not sure because your description is rather hazy.

I know it's not golden boy but I admit its hazy. The guy is working in business and him meeting the girl takes place in the present.