John Gottman's 4 Horsemen

A little about John Gottman. John and his wife have studied relationships for more than 40 years in a lab environment, he has multiple published peer-review journals and is able to predict relationship failure with over 90% accuracy. He’s most probably the world leader in relationships so here’s a tiny bit of what he has to say regarding conflict and how it may help your relationship.
Mr Gottman talks of the 4 horsemen, or in simple terms 4 communication types.
1. Criticism is the most common. It’s not a complaint that concentrates on a specific issue but more rather seen as an attack on the partner's personality or character. This causes rejection and hurt. Eg, You never, You haven’t, You don’t, etc.
2. Contempt. Eye rolling, sneering, insulting, body language, ridicule, hostility. Eg, you’re stupid, you’re worthless, disgusting, etc. This is the most damaging and according to research is the greatest cause of relationship failure (90%) as it damages the person's sense of self.
3. Defensiveness. Generally a response to contempt or criticism and a normal reaction to being attacked. Defensiveness tends to escalate conflict rather than resolve it.
4. Stonewalling. Withdrawing from the conversation. This may occur from the physiological state of overwhelm. Persons interviewed claimed that they were avoiding conflict, but were unaware that to the other person it displayed smugness, disapproval, and distance. It’s seen as disengaging from any meaningful conversation. If one partner refuses to communicate, it can be near impossible to repair any relationship.

The ability to identify the 4 horsemen will go a long way towards better communication styles.
The complaint is partner does not take out the garbage.
I would like you to take out the garbage this evening while I’m cooking dinner, thank you. (Ends with appreciation)
Criticism may look like: Why don’t you ever take out the garbage?
One invites a retaliation while the complaint is seen as a polite request with gratitude.
The use of “feelings” statements can also help and may be important. Eg. I need to ask you for help with taking out the garbage.

Defensiveness invites retaliation. It’s better to take responsibility even if only in part. In the example of garbage, the partner might reply with something like “sorry I forgot yesterday, I’ll do it now, I appreciate how busy you’ve been (appreciation is shown)

Stonewalling to escape conversation/conflict. Self-soothing can overcome this by taking time out and returning to the conversation after the physiological state changes which is normally around 20 minutes, then the conversation may continue in a more respectful and rational way.
Expressing gratitude, appreciation, affection and respect for your partner goes a long way towards building, repairing and maintaining relationships and as relationships are a bit like cars, they require maintenance. Neglect them and they’ll break down.