Need Advice

My boyfriend for 2 yrs has an 11 yr son.. the mother of his child left his son on his doorstep when he was 5 months old & she moved to another state. Everytime he post a pic of his son on social media. She FACETIMES him... not their son, my boyfriend! Am I wrong for feeling crazy? Why does she have to FaceTime him, why does she have to see his face.. why she can't just call him? Then when I ask who is that on the phone, he turns the phone around... she always looks different, & I don't recognize her because she's never around. so I'm like "who tf is that" & he just keeps turning the phone around. I need advice