So there's this girl that I plan on asking out for some coffee/tea. And during our sit and drink, I plan on asking her out to dinner. But before I do, I wanted to see if she has a boyfriend. Either by having a conversation around it or just asking her straight up. My question is, what if she says "I have a boyfriend." What do I say or begin to chat about next? Do I just casually change the subject or do I acknowledge it and just move on? What do I say to her next?

Thanks.