It sounds like the other issues have entered the bedroom, not any problem with your physiology. I don't know why your wife even told you that she thinks you have not been lasting as long in bed and that it bothers her, most women would handle it by trying to help you last longer and blaming themselves, not turn around and make a comment designed to put you down, keep you on a string, and give you performance anxiety. Performance anxiety puts things into a downward spiral even in the best of relationships, but I hold that there is no place for it in a happy relationship. When I hop into bed with my husband, neither of us knows for sure where it will end up, and all possible destinations are perfectly fine with us. Nor is there a good place in bed for feeling like it is do-or-die for you to give your wife an orgasm. If sex is a contest fraught with worry, no wonder your penis gives the whole thing a bye. It seems like you think if you don't have perfection in bed, she will find you an unattractive spouse and leave, and she sounds like she has not done a lot to assure you that is not true.
Don't know what to tell you except that in therapy, you should address her tendency to want to hold the upper hand instead of holding a partner hand with you.
Not a very good way for her to handle this. She should state it as lately she has been wanting stimulation to last longer, as if the change is for her, not you. That would be tactful and you would take an interest in spending longer on her, rather than feeling hurt and worried. I think you are fine and just lost your confidence. Generally if you give a woman attention and spend time on her, it makes her feel good. Sex may change over the years, but kindness and respect and cooperation should not.
I find it interesting that the first two responses were from women. Ladies, thank you both for your response. It doesn't repair the situation... But it is nice to hear. I won't talk about this situation with anyone. It's too painful and embarrassing.
You should talk in therapy about the power dynamics in your relationship, though. You don't have to talk to a therapist about what is happening in the bed, but if you want the relationship to continue, you have to talk about all this passive-aggressive (or just plain aggressive) behavior.