Here's an over-explaining.
1. It's ○ックス.
2. Tifa thought it's f*ck (セックス).
3. Cloud went with Zack (ザックス) Fair.
4. The door opened, but Tifa pushed him down anyway.
Thank you. Have a nice day.
Sometimes the author(cacomistle_tail) did not clean the bottom part.
As you can see in this version and original, the slice of Mary-san's cheek/chin doesn't make sense for the missing panel
PS. I also forget to remove these bottom parts sometimes.
Sauce
The author didn't clearly state the reason. It could be something IRL preventing him to write and draw consistently, but he is now posting more frequently.