No they didn't have sex all the way. This was revealed in the chapters afterwards!!
Uhhh what?? Did you mean the part where haru lost his memory because of car crash?
What chapter
If ur talking about ch32 which is when haru lost his memory due to a push (from his ex-customer), and turned into his 17 year old self. Haru and Ren never did it fully since Ren ran out before Haru could get the condoms. PS- there was no penetrative sex, only foreplay (fingering and handjobs from what I remember)
Ch 34 and later also implied that Ren was still a virgin because Haru and Ren's classmates was teasing him about emitting a virgin-like aura.
Haru lost his memory in ch29 I think
I remember watching the anime few years ago and I loved it, Haru was always so sweet to Ren now I'm reading sine chapters from the manga and wow, I'm so disappointed the author made Haru lose his memory only to make them have rough loveless sex for the first time? All this time waiting for them to make love how they deserved only to rush things and make their first time angsty and ugly?