Im having same problem now(feb 2022) Still no solution? In my case they were a romantic interest as adolescent but later change to acquaintance(maybe as they grow up,since one grew later than the other)
EA Staff (Retired)Can anyone who has encountered this issue recently possibly share a save file where you've seen it occur? You can DM me the link to your save, thanks so much!
Instructions for sharing your save: http://answers.ea.com/t5/The-Sims-4-Bug-Reports/INFORMATION-How-to-Send-User-Files-to-The-Sims-4-Team/m-p/6065302
In my experience the problem of sims with max friendship/love bars remaining aquaintences is because they are best friends, seems you can't be a soulmate and a best friend at the same time. Not sure if this is the cause, but it's a link I have seen several times .. have to choose, best friends OR soulmates, not both ¯\_(ツ)_/¯
