~Smirks~
Personal reasons are personal... maybe she's ill, maybe there were family problems... who knows, who cares? As far as I see it, a Damien Rice gig needs only one person there - Damien Rice. Yeah, Lisa/Shane/Vivienne/Tomo add to it, but as long as there's him there you'll hear sweet music...
Saying that, I've only ever seen him when they've all been there... so I cannae really empathise too well