Less SFX than expected ... for now.
So who is going to interrupt?
a) Mom (probably then telling them to continue)
b) a maid
c) mom & maids listening to the door and the door falling in
d) a rival attacking
e) something else
F) Nobody
Should be either a or c by how this manga usually goes. They already have approval of Tadokoro mom, so Sakurako mom is up next, especially since she was just introduced last chapter.