Rokko can't propose Rita until he has a ring.

Did you talk to Rokko. He said the architect knows where to find these. Find the tailcoat first.

So, you have the tailcoat. But the ring wasn't back there, yet.

Didn't the bowling ball have the portal thingy. Maybe there would be a portal still open.

At the architect's table. Go and see, there is a portal where you can get the ring.