A lot of people have placed restrictions on communication with their partners because of hurt they are yet to heal from or fear of being vulnerable. While it’s not likely that people have set out physical of what not to discuss , they have set the list in their minds like : I can never talk about this or that.

Peradventure their partner mistakenly initiates conversations in that directions, they either become very defensive or recoil and go into their shell.
In what ways are you hindering full communication with your partner ?
Have you inadvertently chosen to make some topics off limit?

It is in your best interest to work out whatever issue that may be hindering you from fully communicating with your partner. There is a clear difference between couples who are free to communicate and those who have restrictive communication.
If you desire the best in that relationship, you need to be able to communicate effectively with your partner.