My favorite part of my job is teaching couples how to respond differently to each other, how to be kinder and more understanding, and how to re-learn positive communication. So I talk about this stuff a lot, and most of it applies to any relationship.
My thoughts are: to some extent we are all guilty of getting stuck in the place where we are just swimming around in our own feelings and not paying enough attention to our impact on others. It is my opinion that the best thing you can do to radically improve your relationships is to forgive people for their self-centeredness, and to recognize and reject it in yourself.
You can mitigate the impact of this habitual self-centeredness by giving your loved ones constructive feedback, and asking for it in return. Accept any critical feedback gracefully, and work on the things you are able to change. Approach all relationships as opportunities to grow and learn about yourself and each other. Teach people how to treat you, and in turn, treat the people you love how *they* want to be treated, not how *you* want to be treated. (**This is an important distinction and the opposite of the "Golden Rule" we are taught in elementary school).
Show where your boundaries are and maintain them. Do not allow anyone to harm or disrespect you, but also accept that people frequently do not know when/how they are being harmful. So when you are hurt, say (out loud) some version of "I don't like when you do that; it hurts my feelings. Can you please do it another way?" and give the person an opportunity to treat you how you'd like to be treated, instead of getting angry or hurt and refusing to offer absolution or resolution.
Remember that you can't be mad about things you never communicated, because no one can read your mind. To expect a person to know exactly what you need, want, feel, and desire at all times is unrealistic and sets you both up for disappointment. Honor your relationships by treating the people you love with respect, communicating clearly about your needs, and approaching them with curiosity about what *they* need from *you* in order to feel better, safer, more connected.