Is it normal for your bestfriend to get jealous of you and your boyfriend

I have known this girl for about two years and we just starting getting close this year, she calls me her bestfriend and I also consider her my bestfriend as well but just a little while ago she started getting attitude with me and ignoring me, when I asked her why she wasn't talking to me she continued to ignore me she then messaged my friend explaining to her why she was mad at me and she told my friend that she could show me the message so she forwarded it to me and it made me upset because she told her that she was upset/angry because she was jealous of me and my boyfriend