Thanks to Sayaka's carefully weighted words, Usa is now convinced that he needs to be the person who can save Ritsu from her own loneliness, leading to him trying to spend time with her whenever possible.
Resisting her hints that she doesn't particularly want him around, circumstances conspire to suggest to Usa that perhaps he's making a breakthrough and getting closer to his senior - however, his reading of the signals she's giving off really couldn't be much more wrong, and ultimately enough is enough, leading to her basically telling him to get lost, which leaves him something of a broken man and her concerned that she's gone too far. This whole scenario is made worse by the lead-up to this outburst, which saw Ritsu bumping into a couple of old middle school acquaintances - an event seen by Usa, and again misinterpreted.
The whole problem only comes close to being corrected when our protagonist overhears Ritsu sharing some of her woes with Shiro - in short, she has nothing against other people, but she wishes that they'd stop with the needless small talk sometimes to let her simply be herself. This comes as something of a revelation to Usa, who tries a new tact of giving Ritsu some space, the only question being how much space to give a girl who missed several changes of lights at a pedestrian crossing because she's so immersed in a book. Perhaps it's a blend of giving her some personal space and acting like his usual self that will finally allow Usa to get closer to her?
Given that she's by far my favourite character in this series, a whole episode dedicated to Ritsu's personality and an opportunity to delve a little deeper into it is exactly what the doctor ordered - this perhaps wasn't the funniest episode of the series (although it had its moments), but it did offer up plenty of sweet character-centric moments and some pleasing developments between Usa and Ritsu. Hopefully this is the kind of thing that the series can continue to build as it progresses, rather than resetting the status quo every week, as it does mark it out from other anime sitcoms thanks to its soft centre and willingness to use its personalities as more than just the butt of jokes.