Riley's story is pretty straightforward—it's about gaining confidence. He grew up overweight and got made fun of a lot, so he has trouble with body image; him going shirtless in the dorm is new, he never would have done that before this year.
That's part of why he still gets shy about sex despite having some experience now. He's a little behind the curve on being open about it because he avoided making it part of his life for so long. Of course, if you reached the scene in his room, you know that if he trusts you, he is very much a sexual person.
Then there's the Victoria stuff where he's trying to learn how to not be walked over when he is a people pleaser. Being nice and amenable was how he thought he always needed to be in order for anyone to like him. He can learn from Connor that sticking up for himself doesn't make him an unlikable person!