HB: oh I have a bf, don't know if it's relevant or not.
Me: wow, I just met you/ or we just start talking and you already telling me about your problems. Please don't be the rain on my parade day :-)
At this point if she laugh too, we I then engage on another subject. But if she still want to continue talking about it, I just say something silly like, "my favorite dinosaure is x, gotta love animal planet/ history channel, you?"
Because I believe bf destroyer works best face to face as you can read her body language and calibrate her better while showing stinger alpha trait than her bf, and appearing unaffected by her having a bf, which can be hard to express in text messages.