Just tell the out party they're out. 8 years ago, a 4 piece band I was in split up. To this day, the rythm guitarist thinks we fired him and moved on, the bass player thinks we didn't want to go on without the rythm guitarist. The truth? We fired the rythm player due to drama, got tired of the bass players drama and bailing on practice, and got busy with life stuff and never found replacements. Now hardly seems like a good year to start looking though......... Just tell them your moving in a direction they don't seem like a good fit for, because that direction involves showing up to practice.