The verb "seguir" has a more literal sense. If you want to mean you are following what someone is saying, you can use the verb "entender" (to understand) ou "acompanhar" (to follow). Anyway, "entender" is more commonly used.
If "o marido" without a possessive indicates the speaker's husband by default, why does not "a mulher" mean the wife? Its the same as body parts and clothing. On the contrary, i would look for a demonstrative "that woman" to indicate some woman other than the wife.
I am guessing it's because "marido" only means husband whereas "mulher" can mean both woman and wife. It seems to be the same as in English where people use "my woman" or "your woman" to refer to one's partner.