Why don't we choose to fix our relationship instead of breaking off?

When some person post here about the issue related to their relationship I see many people simply just telling them to break up. Most of the time.

Yeh I know sometimes that's the better option when there could be no solution, like when we are with toxic partner or in toxic environment or when two completely incompatible or mismatched people came into relationship just only because of attraction or anything else what's not so basic requirements in relationship. I mean not so strong piller.

But most of time, when there is who average person are together why don't they try to fix their relationship? Why now it is more focused on self these days? For example when we ask reason they simply says things like "i don't like what they do" something like that excuses.

Also now there are new terms like "situationship" , "commitment problem", "not available emotionally", "rebounding" etc are another way to give excuses to say I'm more focused to myself than to you.

It's a relationship. Relationship needs learning together how to fit with eachother. Nobody is perfect so no relationship could be perfect. We have to make it perfect. Why we often choose to break up than to learn how to make things work how to fit together? Seeing deep into our problems.
Why don't we choose to fix our relationship instead of breaking off?
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