I'm trying to find yaoi mangas

The first yaoi manga I'm trying to find is about a highschool student who went to the chem lab and met a guy. They got to know each other but the both of them noticed something off but they ignored it anyway. Their feelings developed and they had sex. Uke was left in the chem lab ass naked and shortly after he woke up, his father arrived. It turned out that their timelines overlapped and thus meeting in the chem lab once in a while.

The second manga i'm trying to find is about a guy who likes his uke very much (the manga started with them not being a couple, I think?) but whenever they had sex, the uke doesn't get off. The seme was concerned bc he was thinking that the uke wasn't pleasured while having sex. So the seme assumed (or someone advised him, I think) that maybe the uke has some kinks. He assumed that the uke likes S&M but the uke denies. Shortly after, the uke was waiting for the seme in the room, but he saw a rope (??) and he was curious so he tied his hands by himself. He was too successful bc he can't untie it (lololol) so when the seme arrived, the seme went to the uke and had sex with him (with the uke's hands tied). After they had sex, the uke explained that there was actually a problem (i forgot lol) that he can't get off after sex (I think??). Uke said that whatever they do gives him (uke) pleasure.