Can benadryl (diphenhydramine) usage over a long term produce cause similar sexual side effects that ssris produce?

Unlikely : Ssri side effects are very well established where as antihistamine use and sexual side effects are not that well established . I would be more concerned about long term use of antihistamine and the reasons for it . Are you using it for sleep , allergy ? Consult a psychiatrist as theses may be residual sx of depression and treatment may need to be optimized.