I'm an East Asian guy living in East Asia (multiple countries), and sometimes when I'm with a white guy, lets' call him Bob, for example in a cafe, canteen, or even on the street, a few girls approach us. In most cases the girls are friends or acquaintances of Bob, but sometimes they are just strangers.
When the girls approach us, they start to talk with Bob, and I'm fine with just waiting for a minute. But in many cases, they want to talk longer, and I generally get bored so I go away alone or use my phone. But this does not always work, since often I can't go straight away, like sitting at a cafe or waiting for the next class in my classroom.
Now, the problem is the girls are uninterested in me and they only want to talk with Bob. Usually when both of us had the first eye contact, the girls on purpose look away, as if they saw nothing. I'm totally fine with the girls not being interested in me so I use my phone while they are there.
What annoys me most is that Bob starts to force me into the conversation or introduce me to the girls, like:
This is (insert my name), my friend/classmate/neighbor!
But I know the girls aren't interested in me, and so it is very uncomfortable to be introduced in such a way, in which case the girls usually grudgingly nod a little, or smile bitterly.
Another case was when Bob abruptly asks my opinion about the topic, like:
How about you? What do you think?
When I respond, the girls treat it as if I issued nothing, and all of them return back to their own conversation. These situations are very uncomfortable for me, and I rather want to be alone, without being disrupted, but Bob constantly wants to force me into the conversation.
What I find even more annoying is that Bob refers to something I have in common with one of the girls:
(To the girl) Do you also use it?/Are you also that? Then it's the same as him! (pointing to me...)
At least I'm sure he does not have any ill intention nor desires to mock me, and instead he just wants to include me as he likely thinks I feel isolated.
How to tell Bob I don't like to join the conversation as I think the girls are not interested in me? How can I get Bob not to mention me or force me into the conversation?
Preferably I want to tell him in advance, before it happens again.