I find it amazing that he isn’t sporting wood throughout these encounters. Are we sure he’s okay?
Maybe its like sort of defence mechanism? Like his brain knows that if he gets a hard-on there and then - it will be end of his life? Sorta like you could get stiffies in classroom - sometimes exactly before it was your time to go to black board

, but somehow magically when it was swimming classes - no stiffies there like your own brain was trying to save you? Or was that just me rofl?
Also to be fair, if you analyse their relative positions, you can see on some of the panels that she sits more like in middle of his thighs - aka there is visible space/distance between his crotch and her body, so if she didn't look at his crotch to see if he bulged there it shouldn't kill him if he did sport a wood. Also depending on how fluffy/sensible the story is, even if he did sport it and she saw/felt it - best case she would just get red, call him a perv, and then be all giddy and happy about it later that she makes him horny?