Availability bias can fool us into putting value on the wrong things.
Availability bias, or availability heuristic, tells us that the thing we can recall the quickest during an argument or debate, or the memory that had the most impact on us emotionally has the most importance. As you can imagine, it can trip us up in our relationships.
We tend to stick with the idea we have at the forefront of our minds because it’s usually safer to stick with what we know, and researching other points of view takes time. And if something has been observed by us, instead of just read about, we tend to overestimate the importance of it. And of course, a memory with a lot of emotion tied to it (positive or negative) tends to pop up in our minds first.
Availability bias tells you that if a previous partner has cheated on you, and those painful memories are fresh in your mind, you are more likely to assume that your current partner will cheat on you. This applies even if your current partner has not shown any signs of cheating.