Confessions and dating should not be the final step in typical romcoms. There's still plenty of possible plot points to explore and conflicts to be overcome by the new couple as we see here; that said, there's probably a little too much going on all at once in this manga.
Kenji is an OK friend. Our male lead needs an ally or two in this rather hostile environment. But damn, this wannabe playboy Shishido is super annoying. I hate it when love rival characters don't know when to give up, especially since the main couple is already dating and he already got rejected.
I wonder if this is the price to pay for early confessions and dating in a romcom? I'm seeing obstacles to progress every step of the way... we avoided the typical "will they won't they" romcom dance, but I hope not at the cost of grudgingly slow progress that our main couple has to fight tooth and nail to push through.