Well, as a woman who has experience with getting penetrated from behind, i can understand where both are coming from, because, if you dont get prepared carefully it hurts, A LOT. and bleeding out of your butt is no fun and pooping the next weeks can hurt, if you got it bad, you might even need to see a doctor.
Well, there aren't putting that as a reason tho, they both just dont want to. lol. I hope sensei will make them switch, that would be nice for a change, in the manga world, where theres one uke and a seme.
Honestly, the kids probably don't even know about preparation and bleeding...
Tru ╮(￣▽￣)╭
Why are you both so against bottoming?!?! If you truly love each other, then you wouldn't mind bottoming for your lover! Also, you can simply be a reversible couple! Just because you are the one putting it in doesn't make you any less gay than you already are!