I believe this blackmailing could be the reason why Hotaru is going out with this dick in the first place. Like maybe he's already blackmailing her with something? I wouldn't be surprised if she was a victim. :/

That's what I was thinking too.
Fujiwara really is a [insert insult of your choosing], so I really don't understand why Hotaru sticks with him?
People usually stay in abusive relationships because they care about their partner, but Hotaru doesn't seem to give a damn about him, so... either he has some dirt on her and is blackmailing her, or she's afraid he'd get violent if she breaks up.

But it's really about damn time Yuma finally realizes that what she's been doing with Hotaru was cheating. I don't mind infidelity in stories, but I really hate the "it's not cheating if it's with another girl" trope.
Though I like Takeda's attitude. He seems to be handling their relationship with a lot of maturity.

most than cheat Takeda with Hotaru is cheat Hotaru with takeda, and it's not cheat because she don't like the poor Takeda(she think but actualy she not). to Hotaru, Fujiwara is a "stress releasing/make Yuma
jealous/hurt herself" toy. have something at 3? Hotaru+Fujiwara+other= yes Hotaru+Fujiwara+Yuma=impossible(Hotaru will kill, literally, Fujuwara even if he look at her).