I disagree with the first 2 points. If you needed the day off and there was a healthy balanced relationship, your manager would have accommodated you. It is important to recognize the difference between healthy and unhealthy relationships vs good and bad relationships.

A healthy relationship is when synergy is achieved and people act as a single unit to take care of each other and move through their situation. An unhealthy relationship is when a relationship involves a hierarchical system where 1 person attempts to overshadow another. Remember that managers have the authority to direct you, but they also have the responsibility of ensuring you are being accommodated within the confines of work expectations.

Now you may have had a good relationship with this manager where you were friendly and enjoyed their company, but that is completely independent from being able to properly work with this person. It also works the other way as well, a bad relationship doesn't necessarily affect a healthy relationship because if both people are working in synergy they may not even talk to one another directly.

The rest of this article almost explains that since you mentioned you have to overlook another's flaws but the otherside of this is also to recognize that it isn't just you that needs to do the overlooking. There are times when 1 has to win an argument since the other is completely wrong, they won't like you for it, but if they cared enough, they should overlook their feelings as you overlook their flaws.