Complex sentence: After the party, Roz doesn't really want to go home as she'll be all by herself as Alice is at her grandma's, leading to Frasier and Roz spending the evening just shooting the breeze.
Split into simpler sentences: After the party, Roz does not want to go home as she would be alone as Alice is at her grandma's. This leads to leading to Frasier and Roz spending the evening just shooting the breeze.