In my assumption I think that she will help him to get better with treating girls normally and on a relationship base (helping him to create a better vibe during conversation and daily life). The new learned stuff he could also use for his sex session (perhaps they will have one too). This can help him building up confidence again (and curing his ED problem?!), so that he can face Agawa and the other ones again. Like Shina did help him with his school stuff, Shige could do the same for life stuff. Seems like his little friend showed a little reaction to her gross comment xD
In my opinion Agawa will catch them together in secret not knowing what is between them. Probably assuming that he found a new fwb, although she said to forget it all. Another possibility is that Shige will tell her, that they spend time together leaving out what they do. This could awake a jealously in Agawa again trying to get in touch with him again. She knows that normally Shige didn't like Gotou much and accused him of boringness. The only positive fact Shige knows from Agawa is: he has much stamina, which could have awaken her interest, also after seeing how Shina clings to him. So Agawa could only assume that both of them have sex, making her potentially think why many are after Gotou now. Making her hear sting or question what the other fwb of her miss that Gotou had (beside stamina).
That is just my point of view and speculation what could happen in this volume between Agawa and Gotou! I just hope that Takeda will not milk this new problem too long. It could hurt the plot much imo.
EDIT: This post is from last chapters comment section.