These are what we call the 'YMMV items.' Things that some people find in this work. We call them 'your mileage might vary' because not everyone sees these things in the same way. This starts discussions in the trope lists, a thing we don't want. Please use the discussion page if you'd like to discuss any of these items.
"Funny Aneurysm" Moment: In an early chapter, Shuichi gets into a fight with Hiro at school. Shuichi goes to Yuki's house to avoid his mother seeing him all beaten up. When Yuki sees him, he jokingly asks if he had been gangbanged in gym class. A few chapters later, Shuichi actually does get gang raped.
Unfortunate Implications: The treatment of rape in this series is often seen as extremely offensive. A glaring example would be Shuichi being brutally gangraped by Yuki's bitter rival Taki Aizawa and his group, who do this specifically as revenge against Yuki... and he shows next to none emotional repercussions afterwards. (It's not even asking for a total sobbing/suicidal breakdown from Shuichi's part, but at least for him to acknowledge that it was a bad experience — instead of just smiling and being apparently "fine".)
To be fair, though, it's still treated as a bad thing.
It should be noted that the rape is treated as "white knight" moment for Yuki so he can beat up Taki, and not the emotionally devastating moment it should be for Shuichi. Not to mention that although Shuichi is said to be in pain, he's never shown going to a hospital and is implied to be fine a day or so later (and left alone for hours)...after being gang raped by two or three men.
And having a person raped as revenge against another? Specially when the rape victim is the partner who is seen as the "consenting" and "passive" one, and often wimpified to resemble a stereotypical and unrealistic view of women as frail little things? Kinda... crass.
Also just the general romance can come across as disturbing or emotionally abusive to both Yuki and Shuichi at times, with Shuichi following Yuki around (borderline stalking him) at first. More so, throughout the manga and anime Yuki is abrasive and cold to Shuichi and has shades of sexual assault in the manga, such as when Shuichi has a cold early on and only the direct word "Stop" causes Yuki to get his hand out of the former's pants (literally) despite obvious protests from Shuichi and the dialogue following their first sexual encounter, to the point that one could begin questioning what they see in each other at all.