Sorry, but you are wrong. Tybalt blackmails Jill into 3 awkward dates with him, but also into not letting Jill see the MC anymore.
The MC is no longer an unpleasant distraction for Tybalt. At the latest when the MC arranges a date with Jill in EP3, the MC has become a serious competitor for Tybalt.
In EP8, Tybalt is heartbroken, I agree. He talked himself into winning Jill's heart by blackmailing her into not seeing the MC. That's why Tybalt was so angry before the second tennis match.
But he'll probably change his tactics in EP9, if you believe the Rooster preview. Because Tybalt still has a date open because Jill violated the agreement before the third date. She personally invited the MC to her concert at the library. I know, so Josy, Maya and Derek were there too. But Jill also met the MC. And then we have the concert itself where Jill and the MC meet. This is all before Jill and Tybalt's 3 date.
I can well imagine that if the MC chose a different LI, there could be a love fight between Tybalt and Rusty.