As of Chapter 1118, Heiji still isn't able to confess his feelings to Kazuha properly (rather, he somehow forgets), despite the fact that Ran managed to arrange for Momiji to not ruin said confession like what happened so far. At this point, we all pretty much accept that this is a joke that is no longer funny given that it has been repeated far too many times. However, this bring us a question: why is Gosho still adamant at not making Heiji and Kazuha a proper couple yet despite all they've been through together? Why holding them back when most of the other couples are already pass the starting line (case in point, at this point both Sonoko and Takagi have already been considering the marriage prospect with Makoto and Sato)?

Looking back at the other couples, I believe that in order for them to achieve a successful confession, each of them has to overcome their negative trait and past trauma before their romance can blossom.

• Sonoko had to stop being superficial regarding boys and focused more on her sincere feelings before she ended up with Makoto, as well as learned to be more supportive of Ran and Shinichi's long-distance relationship, which is similar to hers and Makoto.

• Takagi had to learn to be more confident in himself (since he's actually younger than Sato by a year or two) that he could achieve anything if he put his mind on it, while Sato had to learn to move on from her past trauma and trust that her relationship with Takagi will be fine.

• Shiratori had to first learn to let go of his obsession with Sato and focused more on what he actually liked about Kobayashi when they were young, with that they were able to build up their relationship again from there.

• Chiba and Naeko didn't really have much problem, so it was just the matter of moment.

• Yumi had to let go of her little jealousy toward her friends from being in relationship and learned to not jump to conclusion while also trust Shuikichi more.

On other side:

• Kogoro and Eri do know that deep down they do need each other in their life, but their personalities make it that they cannot spit out their true feelings. Kogoro might also feels that he had been holding back Eri's potential as a talented lawyer and her career advancement during their time together.

• While Conan/Shinichi and Ran's relationship has moved up to another stage, what's still holding them back is the secrets that Conan/Shinichi has been piling up and hiding away from her, and it will still be as long as he believes that he can protect her from the Black Organization as long as she doesn't know them.

Meanwhile, from what I've read and watched, Heiji still hasn't overcome his one negative trait that he has shown since the Tottori Spider Mansion Case: letting his emotion and words out without thinking of the consequence. Him revealing that Misa's suicide was due to Robert's writing most likely had broken Robert beyond repair, which was something that Conan himself refused to reveal in the case since he knew what would come out of such action. Another case where the head priest Shakuren drove a mother of the monk to suicide with his harsh words also share similar theme, with the priest himself even warned Conan/Heiji/Kogoro to not commit the same mistake as him given their detective nature, as one's words can become weapon that destroys lives if used incorrectly, which Conan actually noted (albeit comically) that Heiji still didn't understand it. Notably, we still don't have a follow up of this arc since most of the chapters/episodes featuring them always end in a somewhat comical way with their relationship not advancing any further, baring that they at least acknowledged their attraction toward each other.

So inclusion, we do need a long, dramatic, stressful, and meaningful case starring Heiji and Kazuha for Heiji to properly understand this issue of his, preferably with a flashback to Robert's case, and finally confess what he truly think of her without anything holding back anymore, and hopefully this will tie into the next Movie as well.