How do you understand meine Freundin in the following sentence?
Oh nein, er liebt meine Freundin.
Does meine Freundin mean my girlfriend. Could it be my female friend?
Do I have to say eine Freundin von mir to refer to my female friend?
Vielen Dank!

Question

Answer

It could be my girlfriend or my female friend. Yes, it is ambiguous, and the correct interpretation, like many things, depends on context.

Answer

To me it seems like they’re referring to a girlfriend, but it could also be a female friend. You might get it from the context.
To make 100% clear that you’re not talking about a romantic relationship you can always say “ein/e Freund/in von mir”.

Answer

It is not clear from this sentence. It can be the girlfriend as well as just a female friend. The text before this sentence should have set the context.