Some very thoughtful comments here.
Yes, communication, discuss it with an approach that is curious and open, so that she doesn't get defensive or feel attacked. Maybe a "Hi honey [or insert pet name?], I haven't seen [insert name] hanging out with you lately and wondering if you'd like to talk about it?"
I mean that's a very mediocre example, so make it your own.
Also mention in the talk if it affects you?
I was with someone I love immensely and became his everything. And when most of his friends and family left him, or he angrily cut them off, I was there for him. The pressure of being friend, lover, confidant, planner, manager, therapist, and emotional crutch was intense, but I handled it.
I encouraged him to join a group, find a book club, a therapist, a men's support group, a Meet Up, re-join sports, etc. but he always had a reason to shoot all ideas down.
(yes, "love," present tense as my love for this being did not die, just changed)
