The episode made it clear that Bojack had sex with Emily because things were going well with Todd, and so he acted out and did something specifically so that he could damage his relationship with Todd, so that when his relationship eventually falls apart (because Bojack feels that every relationship he is in falls apart) he can look back to the bad thing he did to Todd and blame that for why Todd left him, not because Bojack is inherently poison that drives people away.
What? Bojack literally says “I was lonely, she was there, why does anyone have sex with anybody?”
Neither of them were trying to hurt Todd at all.
The episode made it clear that Bojack had sex with Emily because things were going well with Todd, and so he acted out and did something specifically so that he could damage his relationship with Todd, so that when his relationship eventually falls apart (because Bojack feels that every relationship he is in falls apart) he can look back to the bad thing he did to Todd and blame that for why Todd left him, not because Bojack is inherently poison that drives people away.