Avoiding physical contact, usually appears as a symptom in people suffering from obsessive-compulsive disorder.
Too often, bipolar patients have co-occurring mental disorder, and, OCD is one of them.
Acting differently than before, can mean that he probably switched the episodes (increased sexual appetite and excessive self-esteem during manic episode make bipolar patient engaging in frequent sexual acts, having "hot and great" sexual life).
Shutting down and avoiding physical contact, sometimes is a depressive symptom.
Is he taking meds on regular basis for his bipolar?