A spin-off from the Christian punk-pop group MxPx, Arthur invokes the romantic innocence of ‘50s-era rock, both musically and lyrically. Listening to the bittersweet tunes on Watch the Years Crawl By, it’s easy to imagine lead singer Mike Arthur Herrera ringing the doorbell of an estranged girlfriend with a bunch of flowers in his hand. “Tuck You In,” “To Have and to Hold,” “Fortissimo” and similar tracks are unguardedly tender, carried by Tom Edmund Wisniewski’s crisp guitar strums and Yuri Zane Ruley’s succinct drums. Herrera sings his diary-like lyrics with an earnest yearning, betraying only a hint of the cheeky humor coloring his work with MxPx. “Cold Outside” and “America” kick things into a higher gear with their buoyant choruses, while “You Bring Me to My Knees” and “Heartache” take a sharp turn into power-pop territory. Though almost all these songs deal with boy/girl matters, “Be Still” manages to ask searching spiritual questions as well. Nearly eight years in the making, Watch the Years Crawl By is music meant to inspire love letters — or help nurse a broken heart.