IMHO your sex problem, apart from being the main obvious issue, does cover other problems.

E.g. your wife rigidity, lack of empathy and/or indifference towards your happiness; her fears or blocks about sexuality; her being unwilling to question herself or her behavior (I imagine). Etc. Those were most likely already present before being married; they just were not visible.

Usually, unless one explores and acknowledges what's underneath the sex problem, the latter is unlikely to be solved.