It is so rare for men to share things that can affect their ego. But in order to maintain a good relationship, talking to your partner is very important. If you think your partner is suffering from any kinds of sexual abnormality or any kinds of health problem that involves their "manhood", try to take some time to get information on how you can help your partner without hurting his ego. Reading about different articles that you think can help you understand what's going on would be a big help.
Search online and start reading articles about how to boost testosterone levels, what are the foods you can eat that can help provide nutrients for better sex life, how to deal with your partner having some manhood problem and any other article that can help in maintaining a healthy relationship with your partner.