Well, I'm half right; it's Elly wondering if she should feel guilty about feeling good that Mike is in school most of the day. If it's the one I think it is, her remorse collapses the second he sets foot in the door.
ETA: I'm clearly thinking of a different one because Mike doesn't show up at all; all we see is Elly staring that damned bug-eyed stare of hers because she's conflicted emotionally.
Panel 1: We start out with Elly reading the paper while a slightly-regressed Lizzie sits in her high chair. Elly thought-bubbles "The house sure is quiet without Michael. The whole place feels strange."
Panel 2: As she carries Lizzie down the hallway, she muses that with him in school all day, life is different....easier....peaceful.
Panel 3: As she puts Lizzie to bed, she glares the Bug-Eyed Glare of Existential Horror and asks herself how long is she supposed to feel guilty for enjoying it.
Summary: This is a portrait of a woman who never really, as
howtheduck said, embraced being a mother; she knows she's supposed to regret the passing years and, when all is said and done, will sit in an empty house and wonder what happened that kept all the magic that she was promised from happening. Too bad she doesn't realize that her bad attitude kept her from the life she was led to expect.