Why does my BEST friend keep Facebook messaging my BOYFRIEND?

i dont know how ur friend is, but either shes extremely too friendly, or she is jeleous of ur relationship with your new boyfriend and wants him for herself and is using ur boyfriend for dating advice so that she can have an excuse to talk to him, but when she wakes up in the morning and the first person she texts is your boyfriend may mean shes up to no good, if i were you id check it out.