When you really stop and think about, Homer and Marge didn't need marriage counseling to solve their problems. No seriously, during the whole group discussion thing, Homer had nothing really to say about Marge, but instead Marge went on listing all the things wrong with Homer, and Reverend Lovejoy didn't even give any feedback. Which wouldn't have mattered anyway since the next morning Homer is on the Lake fishing trying to catch General Sherman. And then he succeeds, and is confronted by Marge. Plus if you really think about it, General Sherman is a pretty worthless thing to care about since it's a giant fish in some generic lake in the middle of some generic fishing community, so yeah Homer was being selfish here in conjunction to something that wouldn't at all mean anything in his normal life, he simply didn't want to be there and will do anything to get out marriage counseling, even catching a huge ugly catfish. By throwing the fish back into the lake, to show Marge, he still does love her enough to throw away a petty victory like that in the grand scheme of things. I guess the moral of Homer and Marge's relationship is to never demand or ask for perfect and don't let one bad night ruin your entire life.