Most probably the one you already know; https://www.mangago.zone/read-manga/here_u_are/
And
https://www.mangago.zone/read-manga/the_god_of_pain_s_groom/
And there is an another one. I will share with ou as soon as I find it’s name.
1. This one was cute as hell
https://www.mangago.zone/read-manga/starting_with_a_lie/
And it’s sister
https://www.mangago.zone/read-manga/all_of_you/
Although I don’t know if you can consider this as slow burn
2.sweet as sugar;
https://www.mangago.zone/read-manga/path_to_you/
3.and this one is not a slow burn but a long burn. I suggested this one knowing that it is not shonen-ai and it’s an old one. However in this story the author doesn’t make the sex main topic. They make it as a part of the story. And there is communications, green flags and real life issues about LGBTQ community and people rediscovering themselves. I think I will suggest this one always. Here it is. Hope it’s matches your taste.
https://www.mangago.zone/read-manga/haru_wo_daite_ita/
And after searching for you I realized that I don’t have a patient to read slow burn manga’s, unless there is logical events shows up in the story to keep it going
(*ˊᗜˋ*)/ᵗᑋᵃᐢᵏ ᵞᵒᵘ* I already read Haru wo daite ita and liked it, they're both cute.
The 2 other ones are on my want to read list, I think they're manhuas.
Path to you, I haven't seen this one yet, but I'll read it.
Thanks again for taking the time to search for these.
I'm reading SaYe for the moment :)
Your favorite shonen-ai, slow-burn BL