As far as shamelessly repetitive and unimaginative genres go, you can do worse than the "Childless-Urbanite-Inherits-a-Baby" one. Sometimes they're actually kind of funny, and even when they're not, there are far fewer of them than there are bad rom-coms and bad horror movies (clearly the two most shamelessly repetitive and unimaginative genres in existence) so you have less of a chance to accrue a white-hot hatred of them. Literally the bare minimum anyone asks for with these things is that you shake up the formula a little bit and do more legitimate screenwriting than taking the Raising Helen script and changing the character's names and locations and calling it a new movie. But, unfortunately, Life as We Know It didn't care to put in that much effort.
Remember how Dawson's Creek got pretty unwatchable (more so than normal) for a while there towards the end? This really feels like that, and not just because the former Joey Potter is in it, but because everyone just seems like they came straight out of Capeside and landed in this post-college horrible nightmare. There is a group of friends who have a weird incestous relationship where they've all basically hooked up with each other at some point (aside from the brother and sister), some characters have purposefully weird names like Minnow and Tripler, Katie's character can't make up her mind (shocker!) and she has a best frenemy who is blonde with big boobs. And so there's not a creek, but they do spend the majority of the time by the ocean. Oh, and they all talk like they're sitting around discussing philosophy all the time, with big five dollar words and attempts to make frivolous things sound lofty and important, and Josh Duhamel's character recites poetry. It's all completely believable. I assure you.