Jane your best friend and her Boyfriend

You and Jane met at a young age going to the same primary school. You became good friends early on and have continued to be even into your adult years when you became best friends. However, ever since Jane mentioned that she had a new boyfriend she has become less and less interested in spending time with you in favor of hanging out with Mason her boyfriend. You have met her boyfriend on a few occasions and he seemed normal to the point of it feeling fake, but you never had proof that he did anything other than love her. She never complained about him, and never engaged with you when you tried to press her for details on how he treats her.