Crin dear, I am on a different computer. I put Sims 4 on it and started a new save. I got weird results, but not as bad as the other computer.
I met 1 sim, built up some romantic interest, went home, and was not able to Ask on Date by phone or Relationship panel. Did the Relationship panel never work when they aren't at your sim's house? I could have sworn that it used to.
Then I went back out, met a 2nd sim, built up romance bar, and "Ask on Date" appeared as available on my phone and showed both romantic sims as being candidates for asking.
Then I had one over. My sim could ask both her and the other interest on date through phone and the one on the home lot in relationship panel, but couldn't ask the other sim through relationship panel. (Maybe this is normal.)
Then I broke up with one so I would have only 1 romantic interest again. The Ask on Date phone interaction, thus far, is staying available. I can't ask her on a date via the relationship panel when she is away from my sim's lot, but I can use the panel if I invite her over (which is strange because the interactions on that panel look like they are mostly for remotely calling a sim.)
This might mean, though, that if I choose to have a Sim only ever flirt with one other Sim, they might never be able to ask them on a date via phone. They would have to flirt with a 2nd sim to get the option to pop up at all. This really seems very strange. I commit a lot of user error. I apologize if this has been normal Simming from day 1 and maybe I only just now noticed how quirky it is. The game did completely break on me once before. The "First Kiss" option completely disappeared on all Sim interactions, and all of the Sims' romantic categories opened up as if my Sim had already First Kissed everyone on the whole world. lol. I didn't report it. I just started a new save and it seemed fine. But all of my Sims lost all of their money and stuff and a lot of the familial relationships are gone because I had to rebuild everything and pull them out of the gallery to start over. So I think my main concern isn't so much a quirky bug. Sims has always had those in spades. Most of them are fixable by going to "Manage Worlds" and coming back or by going to build mode and moving things around. I am just afraid of investing another bunch of hours into building up careers and working hard to reach long term goals just to have this bug spiral into the whole thing breaking on me again. You're such a doll to spend some time looking at this. If this is a typical bug that happens to everyone and won't get worse, maybe just knowing that will reassure me and I can enjoy the game again without worrying it will get worse. <3