Multiple Regression, Classification and Boundary Poins
I think you want a clustering algorithm rather than regression. You will have a decision boundary between clusters of data points which will determine whether that particular point e.g. 5,3 belongs to group (cluster) A or group (cluster) B
Fit your clustering model in x1 vs x2 feature space. Take the image below, we have x1 and x2 as the x&amp;y axis. And then the black lines are the decision boundaries, essentially the model.

You can of course just cluster between 2 groups also, as in your case.
You can checkout different clustering algorithms here