I think i will make another save and try to see if I'm doing something wrong
The roommate's partner wants you to be some distance away for that challenge. If you head toward the park and walk around a bit in that area, an event should automatically fire about sending them a selfie and that completes their challenge.
Even if you fail to do it, it shouldn't be the end of the storyline. They should punish you but then issue you another challenge within a week or two.