['My best friend have recently been spending a lot of time with some people from her work.']
That stinks.  I always feel left out when that happens to me.  Even more so when I know the people from my best friend's work so when I can't be involved, its hard.  How do you feel about it?
My best friend have recently been spending a lot of time with some people from her work.  It seems she doesn't have much time to spend with me anymore.