Taylor Swift wowed fans in London with a live debut of "The Black Dog" from her latest album at Wembley Stadium. The surprise performance also included a mashup of fan-favorites "Maroon" and "Come Back... Be Here." Many speculated whether songs like "London Boy" or "So Long, London" were nods to her ex, Joe Alwyn. However, fans now believe "The Black Dog" may be about The 1975's Matty Healy. Alwyn recently spoke out about their breakup, admitting the challenges of ending a six-year relationship in the public eye. Swift's acoustic sets have become a highlight of her global tour, with surprises like the recent debut of "Carolina" in a mashup at Liverpool's Anfield stadium. Fans can't wait to see what surprises Swift has in store for the rest of her tour.