Relationships can be such fragile things. I know I have been guilty of making both of the following assumptions that have led to the ending of relationships.
The first assumption we often make is that the other person in the relationship remains unchanged. Not everyone broadcasts the major and minor changes impacting their life especially in casual work or activity based friendships or in important ones if we have a lack of good communication and listening skills.
All of a sudden they act out of character or blow up in situations they handled differently in the past. We either immediately think it is something that we have done or they have gone off their rocker and avoid them or fight them. We feel like we are in a minefield.
In the case of casual acquaintances we often don't know the circumstances of their lives. They may have had a sudden death in the family, in the process of divorce, their partner lost their job, or a thousand other important issues that have nothing to do with us.
The second assumption is the reverse of the first one. We expect people to be mind readers. We go through a major or minor change and just expect people to notice and understand. After all shouldn't they be paying attention and know what is on our mind and what we are feeling.
We can be guilty of not paying attention to our relationships. We can get too comfortable with them and put them on autopilot and take them for granted.
We don't like being taken for granted so perhaps we shouldn't take others for granted either.