Evening erections

Hi all, can get erections in the morning fine now after many weeks of using the app, however eveningsā€¦ at most I can only get a semi. Been with my wife for 12 years now and nothings changed between us feeling or sexually, itā€™s bringing us apart as my wife thinks itā€™s a ā€˜herā€™ problem when itā€™s not. I do work 12 hour shifts but Iā€™m not tired or not wanting it or anything. Has anyone else ever experienced this?