I've written multiplepieces about the complexities of "coming out" for people in the LGBTQ+ community because I don't think it's something that is discussed enough even though make people take it for granted and over-simplify it.
Needless to say, whether or not someone is out of the closet has no effect on the validity or truth of their identity. Some people are only out to their partner or close friends, or select members of their family. Other people still aren't out to anyone. Whether someone is out to the whole world, or just to one person, it is their decision to make it that way and it is their decision to change that. It is never your place to out someone just because they're out to you.
You can see how this gets to be a very touchy subject, right? Especially if you or someone you care about is in a relationship but not out of the closet. You're so acutely aware of your relationship with them and you care about them and you just want to have the luxury of showing it off to the world that other people do. But that desire doesn't outweigh the other person's comfort, whether they are your romantic partner or your friend. If you get into a relationship with someone who isn't out of the closet you have to respect where they are. You don't get to decide to out them just because they're in a relationship with you. If someone confides in you, you don't get to abuse that trust by telling other people without their permission.
This is an important thing to think about and discuss with your partner, because a lot of times the reason that people aren't out to their family, or some of the other people that they see on a regular basis, is for their safety. For some people, safety means keeping a roof over their head or avoiding physical backlash. It doesn't have to be that severe though. Sometimes safety isn't about what you can see, it's about someone's mental and emotional state. People stay in the closet because they know their family or friends or coworkers are homophobic in some sense or another, and they don't want to deal with the questions and commentary from them, and that's just as valid a reason as any.
You can't project your level of comfort onto your partner. It's not your place to out the person that you're with. This means respecting their privacy on all levels. You don't get to out them to your friends or classmates, even if they don't know each other. It doesn't make it okay to out them just because you might not be forced to deal with the fact that you outed them to people. It means that until that person is comfortable with people knowing that they are out of the closet, until they feel like it will be safe for themselves and you, you need to respect their privacy.
Someone not being ready to tell the world about their sexuality very rarely has anything to do with their partner specifically, so don't take it personally if your boyfriend or girlfriend says that they aren't ready to be out to their family yet. It's not because they're dating you specifically, it's usually because of something personal within themselves. If you don't think that you can handle that, respect the other person enough to say so.
Everyone comes to terms with things at different times and at different paces. It's not up to anyone else to try and rush their partner to be in the same spot as them. You don't get to force your partner or your friend out of the closet because it would be "more convenient" for you. It's not about you, it's about them and their growth as a person. Care about them enough to respect that, and respect them enough as people to care about how your actions impact them even when they aren't around.