Anxiety affects us all at various times. It may cause us to lose our ability to think clearly, to manage our own strong reactions to other people, and to calm ourselves down. Where anxiety is more than just a temporary response to a stressful situation, and is so intense or prolonged that we are unable to manage it on our own, it may be necessary to seek medical and psychogical help for what may be a mental illness.
You reach out to connect to your partner, but she is lost in a world of her own. He's sad, but nothing you do seems to help. No matter how you encourage, nag etc she just can't get motivated or excited about anything. You wish he'd just 'pull themselves up by the bootstraps' and 'get on with it', but he seems incapable of doing this.