I was always "agains" DPC on this and not against you personaly. thats why I call this lazy by dev. one decision (not go on date) ruin ALL relationships? sound stupid. DPC just want make you choose for some reason (like you not make a choice in ep8) and make it most dumb way.
legit in terms he already have plans and she just randomly show up so basicly he should cancel them. Jill look smart enough to understand what plans mean.
not sure Jill know they was fuck buddys and you can choose to not be fuck buddys at that point of story if I remember correctly.
Imagine Jill, who jump on every posibility to help others, just come with unplanned visit, hear you will go help friend who is sick and just start bitching "no! sandwichs more important! I don't give a shit about your plans I'M HERE SO ON YOUR KNEES! or no chance for this pussy"

1) this is so out of character for Jill
2) this is lazy way of writing. imagine every moment in game random girl come in room and say "go with me or bye". I wondering how many people in that case still try find excuses for character to do that...
there also example when you can on phone decide to spend some time with Josy and with Maya, and after free roam you decide with whom. well ok, after your choice should second girl just become not available for relationships?..