Yup you are right. The switch of main characters, the lots of side characters that weren't deep explored here, the lots of villains and their barely seen motives and the lost focus on the very main couple was really disappointing. The weirdest part was the few slice of life chapters (around chapter 30) introducing the new main characters.
It felt like lots of ideas but few chapters and time to settle them.
It still was a bit entertaining but the story could have been better executed.