Is there any reason a man who who had an orthodox wedding but only a civil divorce ( a get was never requested nor refused) cannot become remarried by an orthodox rabbi? I am aware of the Agunah problem with a woman but I was unaware that the man would have any problem.

If the wife is still alive there is a rabbinic prohibition, known as "Cherem De Rabenu Gershom", to marry a second wife without Halachacly divorcing the first one.