For Moms with adult male children?

Your son brings home a perfectly acceptable girl FINALLY! And you actually like her. After a year of the two "dating" you ask where things are going and he tells you they are only Friends but you know better. He still lives at home and he is always laying in her lap when they are downstairs on the couch watching movies. Which BTW is pretty much all they ever do. While questioning HER about where the relationship is going she lays it on you that they are only friends and that she is otherwise happily married. I said "Why didn't you tell me" and she said "You never asked". WTF?!?! How do I handle this situation. I don't know what to think, say or do.