Oh good so she does have actual standards, thank goodness. It's good to see the series continue to develop Mashiro's character, slowly- very slowly- pulling her out of that "intimacy = sex" mindset.
As for the boyfriend not getting much attention... In-universe, he's still getting used to being any level of intimate with girls. Mashiro is (mostly) respecting that. Out of universe... Let's face it double standards are in play. Groping another girl is fine (and plenty of people read it to see the busty girls getting felt up) but the moment she starts doing anything with Gentarou that rating is going right up to R-18.
As for the boyfriend not getting much attention... In-universe, he's still getting used to being any level of intimate with girls. Mashiro is (mostly) respecting that. Out of universe... Let's face it double standards are in play. Groping another girl is fine (and plenty of people read it to see the busty girls getting felt up) but the moment she starts doing anything with Gentarou that rating is going right up to R-18.