Advice a friend who respond to conflict by confrontation and why is it not healthy to sustain a positive relationship

Good advice is probably not enough to convince a friend not to deal with conflict with avoidance because some people are so confrontation averse that just telling them why it would be better to face conflict head-on would not be enough. Still, if you tell them why avoiding conflict is not healthy for them enough times, maybe they will get up the courage to try to deal with a small conflict head on. If they do so successfully, they may be able to graduate to dealing with a larger conflict directly. When you avoid a conflict, it's still there and creates stress and anxiety that grows over time.

The advice I would give to a friend that behaves that way is that he or she should react on a more calm way because responding to conflict with more confrontation affects people's relationships in a way that nobody wants to be alongside someone troubled or controversial. People often tend to stay away from this kind behaviors just because they think that these people are hard to get along with.

So, the advice is just to tell him or her that listen to the others and try to fix problems by calmly talking with others so that you built comfortable relations.