He does come across as an over cautious individual. Maybe that's why Mr. Poland had to die, despite not being deadweight or dispensable. Maybe Mr. Poland managed to penetrate something with their rivalry and it put Mr. Lithuania at considerable risk to continue the relationship.

[She says rivalry, but to her the word means something more along the lines of friendship or lovers.]

I certainly didn't see it coming at least, but then again Mr. Poland was not exactly quiet about his intentions to unearth the Mastermind. Maybe he forced Mr. Lithuania's hand. [Actually Mr. Poland wasn't really that quiet about much after that second trial, was he.]

[Siren offers a sympathetic look.] ...Perhaps much like myself you simply chose the wrong person to frame.