I am very happy to state "I told y'all so."
Akira is not a robot unlike the reader commentary following his reaction to Rio's confession a few chapters back.
If you aren't convinced by these last few chapters sub-arc with her, then nothing will.
You can clearly see he's very attracted and possessive of her, understandably so. And he is very open with his thoughts and feelings with her.
She's the most behind "in experience" out of the harem, and he takes that into consideration, even when making out with her here.