EDIT: I have been made aware of the mistranslations. Consider Nagito 3 tiers up.
No love suite included because it's just the characters' fantasy/unconscious desires.
Talks of marriage: Basically all included characters want to marry you. And yes, Teruteru wants you to become his, um, wife and meet his mom.
Basically dating: Makoto flat out says he wants to be with Kyoko, Sayaka, Hina, Mukuro and yes even Toko. Same for Hajime with Mahiru. Akane is more lowkey but she also implies romance. Kaede wants you to visit her house and become closer. And Miu forces a date on you in classic Miu fashion.
Strong romantic undertones: Sakura says that after she fights her beloved, she wants to start thinking of a future with a certain someone. Chiaki and her talk of dating sims. Fuyuhiko tells you that live or die, your life is now his and to not die without him. Hiyoko calls you a special someone she wants to protect. Gundham wants you to live a quiet life with him, just his 4 Grand Devas, their families and you. Shuichi has the classic "I shouldn't be thinking like this for a boy!" about Kaito. Tenko wants you to get a sex change or at least start Neo Aikido to be with her and blushes. Kokichi says he stole your heart and it is now his. Tsumugi wants you to be cosplaying with her when you get out. And Rantaro tricks you in agreeing to spend the lifetime with him travelling around the world.
Platonic life partners: They all make you a proposal to be together with them forever (Celeste makes you a servant, Byakuya wants you to be his secretary, Ibuki and her band, Kirumi wants to be your maid free of charge etc).
Best bros: They flat out call you a very close friend and/or mention how much you've helped them.
Less intimate than most: The focus is more on them, and not on your bond. Leon thanks you for helping him figure out what he wants to do. Impostor thanks you for helping him come out and be himself. Surprisingly Nagito just calls you "a friend". Gonta thanks you for helping him figure out he is a gentleman. Himiko wants to help her find her teacher but that's it. And Ryoma says he wants to slowly build his life back when he gets out of prison.