Hi there! My sim has about two best friends, one old friend and one good friend in her relationships panel. Usually, if you want to go on a date with a sim, you can click on their sim's thumbnail in the same panel and click "Ask on date..." or you can simply click the same option on any phone and then choose who you'd like to take out. However, my sim only has "Ask out on date..." appear on her phone, not when clicking her individual friend's relationship panel portrait. I chose the option on the phone, but it said something along the lines of "Your sim doesn't know anyone well enough to take them out. Go make some friends!" when my sim has definitely had outings with these same sims before and definitely has friends. How am I able to fix this? All the sims my sim wants to date also have a full relationship bar with her.

Thanks in advance!

Adding social interactions to a sims portrait as if you were on the same lot together is a feature of the Nraas mod Relationship Panel,you can't do this in a vanilla game.

Ahh, really? I'm sure I was able to do this before, and I don't have Relationship Panel. It even says it on the Sims Wiki that I can just click their portrait. Likewise, I've been eyeing that mod and would like to get it! Once I put it in my game, will I be able to ask sims out on dates directly from their portrait in my sim's relationship panel?

Without the RelationshipPanel mod, the interactions you can choose from the relationship panel are limited to what you can do by phone (or texting, etc.). Ask out on a date in that context means pick up the phone and ask them out. With the mod, the options that would be available when your sims are in the same place (room, lot, etc.) are opened up. This can actually be unsettling if you choose one of those and find that your sim has to drive or cab across town to fulfill the command in person rather than by phone, but it's still often convenient to have some of them there.

I think the underlying issue is that you cannot ask a sim out on a date if they are "just" friends and have no romantic/flirty history, they aren't yet Romantic Interests, etc. I believe that if you ask them out socially but then start flirting with them, the group outing (of 2) will automagically become a date although I may have that wrong and they do have to become at least RIs first.

Right! I think that's what I've been looking for then: they need to have some sort of romantic undertone to their relationship before my sim can ask them out. Thanks for the clarification with both this issue and the mod!