This is a reference to the urban legend about how the IRL Still in Love started spiralling mentally after seeing her jockey together with his fiancee, though if I remember right the claim is that it happened during the prep for the 2003 Queen Elizabeth the II cup?

Worstar said in comment #2602747:

This is a reference to the urban legend about how the IRL Still in Love started spiralling mentally after seeing her jockey together with his fiancee, though if I remember right the claim is that it happened during the prep for the 2003 Queen Elizabeth the II cup?

Yeah, definitely on the QEII cup