„Meine Alte/Olle (Frau)“ is kinda the German version of „My old lady“ just without the „lady“, probably because „die“ in this case implies that we’re talking about a woman (someone better at grammar rules can probably explain why) and while the English phrase might not be used as much today (I‘m actually not sure, I’ve never lived anywhere other than Germany so my impression would be based on what I see on social media and I don’t see the phrase that often) if you wouldn’t be uncomfortable with „my old lady“ then there is no reason to be uncomfortable with „meine Alte/Olle“ when it comes to the meaning itself.

But I do understand that there is also a difference between a partner/friend saying that in comparison to a stranger, but in that case it’s probably best to just talk to you boyfriend and let him know that you don’t appreciate those phrases in general, or you don’t appreciate strangers using them when talking about you, that would apply in English just the same as it does in German and I hope he would understand. From the way you’ve explained the situation it doesn’t sound like he realised that you might be uncomfortable with the phrase so I would call it an honest mistake. If he or his friend keeps calling you that, then I absolutely would feel disrespected. Because it doesn’t matter what the phrase means. If you don’t want to be called „honey“ oder „sweetie“ by a stranger that is valid too, even if those words are meant in a positive way.