Interpretation R-square in path analysis

#1
Hi all,

I have a question about my R-square in path analysis. I estimated my model in steps. Models 1 and 2 are regressions, the third is the path.

Model 1: contains 3 IV, 1DV (Vaccine readiness) and 3 control variables. They all have a direct effect on Y. RSquare is 0,150
Model 2: contains 3 IV, 1DV (Political preferences) and 3 control variables. They all have a direct effect on Y. RSquare is 0,196
Model 3: Contains 3 IV, 2DV (Vaccine readiness and Political preferences) and 3 control variables. Vaccine readiness has a Rsquare of 0,154, political preferences R2 of 0,04.

All the IV's have a direct effect on Political preference, they also have a direct effect on Vaccine readiness.
The control variables have only a direct effect on Vaccine readiness and NOT on political preferences
Political preferences is a mediator. Which means all the IV's also have an indirect effect on Vaccine readiness.

There is a visualisation (in Dutch) below. You can ignore the 2 headed arrows.

My question for you is: is that 0.154 just the sum of the rsquare of model 1 and the rsquare of political preference of model 3? And what does that low rsquare of political preference mean if you compare it with model 2?
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