If I remember right, Hiker Andy appears in BW2, crying about losing his summer romance, and not being over it.
Whether he actually went out with Hilbert, or is just talking about spending time with him on the Ferris wheel, he's likely found someone else by now.
And since Rosa is his date in BW2, the guy in XY is probably talking about her. Or Hiker Andy didn't tell them about him and Hilbert breaking up because he's too ashamed to say it didn't work out.
