'Endogeneity' and 'Spurious relation'

The concepts of 'Endogeneity' and 'Spurious relation' are perplexing. I m going to illustrate these by a simple example. (But not sure if I m correct)

Recently, I m busy at my preparation for the qualifying exam, thus it is implicitly agreed that I would be discharged from the responsibility of cooking. That is, due to the harsh schoolwork, my housework will be reduced.

SCLWORK --> HSEWORK (1)

From (1), it looks like the increased schoolwork leads to the reduction in housework.

However, 'SCLWORK' and 'HSEWORK' could be endogenous. The causality could be reversed as having little housework leads to more time for school work.

Thus SCLWORK <--> HSEWORK (2)

As a result, we could not establish causality, but only a negative correlation between these two variables.

Additionally, it could be another thing that is affecting my time spending on schoolwork and housework...for example my personality..such problem is called spurious relation.

If I like study and hate housework, I will put more time on schoolwork but less time on housework. Put in other words, the increase in sclwork and decrease in hsework are due to my personality/preference, not because of the variables per se.

My teacher said, it is meaningless to investigate two endogenous variables. I agree. I should not complain I don't have time to study just because I need to do housework...the outcome is just because I m lazy.