Set your boundaries! There should be fewer invitations to become BFF with other Sims.
Fixed in Patch 1.101.290/1.81
Please create a new thread if you're still experiencing this issue,
I have had this bug since purchasing the High School pack. It can be fairly annoying and occurs all of the time. Once when my sims were on vacation, one sim proposed to another on the beach, and just as they turned to marry at the wedding arch, another sim interrupted the ceremony to ask to be best friends. They actually walked through the arch to ask to be besties. It is such a weird glitch. Kind of funny, but weird. I use MCCommand so I can have multiple best friends. I use LilMsSam's mod UnlockDoorforChosenSims to lock sims out.
I turned off the “NPC initiate relationship” feature in Gameplay Options and it seemed to have stopped this BFF invasion although I still have randoms walking in impeded in to my house to pour a glass of water. Ugh. If it’s not one annoying glitch it’s another.
