A major indicator of where to find a girlfriend...

Countries with higher birthrates tend to be better places to find a girlfriend. You need to consider why the country has the birthrate it does.

Anglophone countries (the U.S. and Western Europe mostly) have above replacement birthrates, but this is because of immigration. They are still bad countries to find a girlfriend in because they are feminist and the "native" women have eschewed giving birth. These countries will eventually give way to the new populations (Muslims/Arabs in Europe and Latins in the U.S.) because these countries are committing cultural suicide.

Here's a birthrate map from Wikipedia:

https://en.wikipedia.org/wiki/File:Countriesbyfertilityrate.svg

Philippines is still plenty above replacement, as are many of the poor countries of the world. China has a low birthrate for obvious reasons, although I don't generally consider it a bad place to find a girlfriend.

The three general regions that are good for high birthrates are Asia, Africa, and Latin America.