Sorry to hear what you are going through.
Part of the reason that he gave for his A was that he had only been with me and wanted to know what it was like to get with someone else.
Just my opinion, but the above just doesn't fly for me. It was not an honest answer, just an excuse, just a cover up.
What if I'm not enough for him anymore? What if he wants to explore more and do different things?
What if I'm not what he wants anymore?
He should be at your feet, begging your mercy and forgiveness; doing anything and everything to make you happy and to believe in him.
From the little I know, it all has to do with him, not you. Just an opinion.
Age 33 affecting sex life, I don't think so. Meds maybe, but not 33 years old.