Don't tolerate unpleasant or inappropriate behaviour. Don't let them hurt your feelings or cause you emotional distress. If someone displays a lack of regard for you, that is a clear sign that you should not be around them. That is a clear sign that you deserve so much more.
The narcissist will disrespect you. They will trick you into believing that it's all you deserve and so you cannot obtain anything greater than what they have to offer you. But that is not true, that is just what they want you to believe so that you will remain stuck with them, and forced to tolerate their disrespect. The truth is you deserve so much more and you are capable of obtaining so much more than what they are giving to you. They have to put you beneath them to make you believe that they are all that you deserve, and they devalue and degrade anyone who could potentially give you the care and support that you need. They have to make you believe that you're not good enough for anyone. If that doesn't work, they will make you believe that no one is good enough for you. Either way, it is designed to isolate you. It is designed to contain you, where they can then keep you all to themselves and use you for their own needs.
I want you to know that you are deserving of so much more than what the narcissist has to offer you. You should not tolerate their disrespect, you deserve so much better than that. Don't let the narcissist tell you what you deserve. Don't let them define your worth. It is your responsibility to define who you are and what you're worthy of. Don't let anyone make that decision for you. You deserve so much more, and I don't mean from another person, I mean from yourself. You have so much more to offer to yourself, but instead you are giving it to a person who doesn't even appreciate it. They take for granted everything that you give to them. They don't fully understand, recognize or value what you have to offer them. They feel as though they are entitled to it, but people have to earn it from you. You can't just give it out to people who haven't earned or achieved. That's what leaves them taking you for granted. That's what leaves them to become very ungrateful.
Instead of wasting your energy and resources on someone who doesn't even appreciate what you have to offer, take what you have and walk away. Walk away and give it to yourself. Don't tolerate disrespect from the narcissist. You deserve so much more than that and you will find everything that you need within yourself.