I talk a lot of shit on Rilo Kiley, because it's such a shame watching a group slowly destroy itself. I don't claim to know a lot about the inner workings of the band, and their entry on Wikipedia says nothing about personal tensions in the band, but I have my theories.
I saw them play twice in 2004 in San Diego, and at both shows the audience was composed primarily of 14-16 year old kids who were dressed as if it was an 1980's costume party (in which no one present had been alive in the eighties, nor had any idea how people actually dressed in the eighties). They (and I mean a good majority of the crowd) sat down on the floor while Tilly and the Wall played, back when no one knew who they were, and you know that all of those kids probably worship them now. When Michael Runion came out, he insulted the oblivious crowd by saying, "Hold on a second, just mingle or something, swap MySpace profiles or something..."
The crowd became alert and surged toward the stage when Rilo Kiley came out, creating an solid mass of bodies that stood, without movement, throughout the whole show. Like rabbits standing in front of a giant headlight they want to get closer to, the mass of poorly dressed children just stared, concentrating hard on making sure they didn't touch anyone they were standing next to. Further back you had kids sitting on cellphones, txting away, talking to each other. A couple shouted song titles the band refused to play.
Blake Sennett, Rilo Kiley's guitarist, sneered at the crowd for the most part and hid behind sunglasses (a behavior I did not see replicated when I saw Blake play with The Elected in Los Angeles). The other band members seemed mechanical, going through the motions. Jenny Lewis seemed to be the only person on stage who enjoyed the silent adoration oozing from the unmoving masses of teenagers in front of them.
I don't claim to know what they were like before their crowd turned into a bunch of teenagers, but what I saw was a band at odds with their scene, and probably with themselves since Sennett and Lewis' former relationship couldn't have been good for the interpersonal band dynamic. You factor in Sennett's songs with The Elected about some anonymous female claiming, drunkenly, that their band's only reason for success if her songwriting and that his songs suck, and you start to wonder how autobiographical Sennett's music really is.
Jenny Lewis' solo success, riding on the back of a false southern accent (you're from Los Angeles, honey, not Tennessee), down home folky country girl posturing and the teeming thousands of tasteless teenage girls and boys listening to her relentless shit probably didn't do much to help Jenny Lewis' ego from slowly absorbing whatever good there ever was in Rilo Kiley's music. So, then there was Under the Blacklight, what I'll consider Rilo Kiley's official statement that their period of good music has passed and from now on they'll just be trying to cash in on the name. It's all just a paycheck to them, now. (At least Weezer has the decency to admit publicly that they're only in it for the money!)
It's like when Olivia Tremor Control broke up (except that OTC never got on a major label and never had an audience full of retards to try to cash in on). Hart went on to make music with his set of influences under Circulatory System, and Doss went on to do The Sunshine Fix with his. Only with Rilo Kiley we've got Blake Sennett making good music with The Elected, and Jenny Lewis slowly raping the bloated corpse of country music by singing horrible songs for Disney movies.
I guess you have to play to your strengths.