And ask me your questions
Oh let's go back to the start
Running in circles
Coming up tails
Here's some nice scientific wordplay to describe the narrator's dysfunctional relationship. As it's coming from the narrator's heart, he describes it in experimental language.
"Coming up tails" is a euphemism for how the relationship is going wrong, and in true experimental fashion, the narrator is imploring them to go back to the start and try and repeat what they've tried to do before in the hope it'll produce different, happier results.
Only it doesn't, as the narrator fails to see that relationships cannot be quantified, controlled or predicted like his experiments.