(Original Publication Date, 22 July 1991)
Panel 1: The next day, Liz gleefully twirls around and thought-bubbles "Hah! Michael's GONE! At last, the whole rec room is MINE!!"; this is because when he's around, he acts like a total shit to her. It's the one trait that survives his becoming suddenly wonderful, sad to say.
Panel 2: As she lays down on the couch, she tells herself that she's got the couch, the channel changer, the best cushion, the dog and the popcorn.
Panel 3: We turn towards the sappy when she tells herself that there's only one thing better than having everything to herself.
Panel 4: We see that we're dealing with fridge fodder when she thought-bubbles "An'that's someone to share it with."
Since she's sharing the couch with Farley, it's highly likely that aprilp_katje is right to assume that Liz thinks that a good dog is better company than an ugly brother.
Summary: This looks like her actually missing Mike but as we've seen, Mike thinks sharing is bad and wrong because deep down, he's a greedy little shit who thinks that if he doesn't have everything he sees, he's joined the ranks of the totally deprived. Farley is far better company than Mike will ever be.