Is it important to inform your partner of your sexuality?

This might feel like a callout or be something over discussed. If so, I'll delete.

I'm just piggy backing off of a post I commented on earlier and I want to see a real discussion rather than just people assuming that a differing opinion is someone trying to start a fight.

If you were in a relationship with someone and they didn't disclose to you for a long time that they were attracted to people of a different sex (or gender!) from you, would you be upset?

Further, do you think it's necessary for a kid to "come out" to their parents and family, or should it be okay for them to just bring home someone of the same sex?