The emotional tone of the verbal or nonverbal message is what makes communication feel good or bad. the actual message is secondary. If you want a healthy, loving, relationship it's important that you have a positive tone when you communicate. The relationship call only be as good as it feels in any given moment. Feel good communication is a vital part of this.
The idea is to share good feelings. We all want to feel good, but specifically we all want to feel seen, understood, appreciated and loved unconditionally. do your words and actions communicate this to your mate?
Do you seek to understand him/her? Do you validate him/her? Do you express appreciation? Do you accept him her as is or do you try to change them? Is the tone of your message one that feels good or does it feel like condemnation, resentment, anger or indifference?
It's not so much what you say, but how you say it. The only thing you really need to remember is to communicate (with your words and with your body) with understanding, validating, appreciating and loving intent.