How did it happen.
My simself (me) end having somehow falling out with someone, I was eiding and playing other sims, and when I start playing my simself one of my friends/girlfriends friendship bar are full red but relationship pink bar are half and okay, but when try talk or anything it get worse, I was annoyed cos don't know what my simself been up to when playing other sims. It said we gotten into a fight. Try do anythings but keep getting red negative, find some help google or youtube but struggling. I was frusrated how can be fix friendship and make red bar go down.
Does red bar go down over time? It getting frusrated.
It does go down over time, but I agree with telemwill that you may be inadvertently doing something they dislike. You can also socialize with them using the chat option on the computer and that can also help, in addition to sending friendly messages.