Of course, aha. I feel kind of silly typing it all out but I hope my feedback in any way assists!
That's totally reasonable! For now I'd consider it largely an after-thought but other than that I found the UI to be very easy to interact with.
Jerk characters seem to often be a hit with readers and not with their writers! That said I definitely wouldn't enjoy his route as much as I did without the ability to match his bickering. I think the bickering, at times, is very endearing it just frustrates me to see him jumping back and forth between affectionate and dismissive -- which is an understandable character trait considering his situation. I look forward to seeing him less guarded in the future!
I'll admit dating an ex's little brother is a kind of uncomfortable idea for me. Still, I think getting past that is something I won't be alone in facing, since along the route I imagine Joselina will also have some complicated feelings on the matter. I think it's a great way to draw up conflict around the relationship, though, and am definitely not adverse to exploring his route because of it. And, of course, I'm happy to see more of Sarah!
My suggestions for adding to the design and outfit categories are honestly just things I'm personally fond of. I really gravitate towards large sweaters and cardigans, blazers and jackets in general, crop tops, high-waisted bottoms, and combat boots but that's all personal taste. I'd also really love to see an a-line bob hair style on the longer side as an option for hair just because it happens to be my favorite style. Other than that nothing comes immediately to mind, I'm afraid!