I suck at putting my feelings into words properly, but... One of the things that make ShuAkeHaru so appealing to me is just how much potential there is in there for both angst and fluff.
Like, obviously with everything that has happened it would be tough for ShuAke and AkeHaru to get together, and the ShuHaru adds an extra spice to it.
You have Ren trying to figure out how he actually loves Goro and wants to help him, despite trying to kill him and despite what he did to Haru's dad. And then he has to also consider his love for Haru.
For Haru, it's a very similar situation. She loves Ren, but with this OT3 she also manages to somehow come to terms with her feelings for Goro despite what he did to her father and also to Ren. But despite all that, she still cares for him deeply.
(I will also point out that forgiveness is different from redemption. Haru always makes it very clear that she doesn't intend to forgive him for killing her father, but I think she would still believe that he can do better, as long as he puts in the effort.)
And as for Goro, it's him coming to understand that yes, he can be loved. He's not unwanted. He's not worthless without his ace detective status. Ren and Haru's love and care for him is genuine. He doesn't need to push them away in fear of hurting them or them hurting him.
And once they're past all that, once Goro has decided to stop pushing others away, then you can get to the fluff.
All three of them having dates together. Making coffee, sweets, just cooking and baking anything together.
The three of them running a coffee shop together!
Haru deciding to challenge both Ren and Goro to chess matches, and she beats both of them!
All the cuddling and kissing! (+Goro blushing every time because he's never quite good at showing affection physically.)
And most importantly: All the hair floof!!!