It was a sad and steep fall-off for what was once television's top-comedy as Two and a Half Men had already dropped in its ratings since Charlie Sheen was fired for his off-camera behavior, but when the final season rolled around the ratings dropped even more, confirming it was time for the CBS comedy to call it quits.
Despite ratings slightly rising in season 11, the final season tanked as it failed to have a single episode rate higher than a 6 on IMDb and finished the series off with a finale that rated as the worst episode in the entire show.
Glamping in a Yurt, Episode 3 (5.3)
Part of the premise of the 12th season was that Walden and Alan posed as a couple so that Walden could adopt a child. When their social worker comes over to examine the house and inspect it to make it to make sure it's a stable environment for a child, a wrench quickly gets thrown into the operation when a drunk Lyndsey shows up to win Alan back from Walden. Alan, Walden, and Jenny manage to keep Lyndsey away from the social-worker and she comes to the conclusion that Walden would be a great parent, putting him on the approved list for adoption.
Thirty-Eight, Sixty-Two, Thirty-Eight, Episode 4 (5.3)
Despite a low rating, this one tugged on the heartstrings just a tad. Walden and Alan meet with a mother who is nine months pregnant and decides that she wants to give her baby to the two of them. Ecstatic, Walden and Alan invite all of the guys over and toast to the fact that they're going to be raising a child. In the middle of the party, the woman goes into labor and they get called to the hospital, whereupon the woman gives birth to a beautiful boy... and she decides that she can't give him up and that she wants to keep him. Devastated, Walden and Alan have to head back to the house with no child.
Family, Buble, Deep-Fried Turkey, Episode 8 (5.4)
In the last Christmas episode Two and a Half Men would produce, Walden and Alan try to convince their new foster-son, Louis, that Santa Claus is real by giving him a bunch of toys on Christmas. Unfortunately, the toys don't come pre-assembled and Alan and Walden scramble on Christmas Eve to get them all built. Naturally, they're deterred from their task by several incidents and they end up falling asleep with Louis in his bed... without building the toys. They wake up horrified, but discover that Rose built the presents in the middle of the night so that they'd be ready when Louis woke up. Seemed nice... until she put a video-camera in the present that she gave Walden.
For Whom the Booty Calls, Episode 11 (5.5)
Alan and Walden spent a lot of time together, which meant that Walden got a front-row seat to all of the stupid things Alan did... such as sleep with their social worker, Ms. McMartin.
When Walden finds out, he gets furious (due to it possibly affecting their adoption of Louis) and he decides to join a Support Group made up of other fathers so that he can have somebody other than Alan to talk to. Unfortunately, Alan finds out about the group and the rest of the guys don't mind having him around, making Walden even more frustrated.
Don't Give a Monkey a Gun, Episode 14 (5.5)
By this point in the season, Walden and Alan had successfully adopted Louis and all of the papers had officially gone through, which meant that the two friends were now free to get a divorce. To thank Alan for being such a good friend, Walden allows Alan to pick a gift of his choice (hinting that he should buy Lyndsey a massive engagement ring) - but Alan doesn't care and chooses a Ferrari instead. After some reflection, Alan finally decides that a ring is the right choice as it benefits both him and Lyndsey and he proposes - to which she says yes.
Here I Come, Pants! Episode 10 (5.6)
As stated (and obvious), Walden and Alan weren't an actual couple and only pretended to be one in order to adopt Louis - so, understandably, Ms. McMartin was a tad upset when she found that information out, knowing full well she could get fired for putting a child in such a situation. Alan and Walden do everything they can to stop her, but she winds up taking Louis away from them... only for her to immediately change her mind when she realizes how happy Walden and Alan make Louis.
Boompa Loved His Hookers, Episode 13 (5.6)
Alan and Walden had managed to make it through the entire series without being able to find love (which is why they married each other). But once Louis' adoption officially went through, both Walden and Alan reached crossroads with their girlfriends where they had to decide whether they truly wanted to be with them or not.
Both men end up choosing their girlfriends (knowing they'll never be able to do better) and they both end up winning them back.
Bouncy, Bouncy, Bouncy, Lyndsey, Episode 9 (5.6)
Despite the fact that Alan ended up with Lyndsey, they broke up and got back together more times than could be tracked throughout the six seasons that she appeared, including during the final season. At this point, Alan and Lyndsey had taken yet another break when Alan runs into Herb, who then asks Alan if it would be alright if he asked Lyndsey out. Alan admits that he thinks it would be weird and a violation of the bro-code - only to find out that Herb already slept with her.
Sex with an Animated Ed Asner, Episode 7 (5.8)
Alan and Walden discover that having a 6-year-old boy is quote exhausting and decide to try and take him to a place where he'll meet some friends. Unfortunately, the guys meet a trio of moms whom they befriend, but Walden becomes attracted to one of them (which is a problem since he's married to Alan). Eventually, Walden and the woman end up alone together where Walden reveals the truth about his and Alan's situation - which the woman finds quite sweet. Just as they're about to have sex, Walden gets called into Louis' room and ends up falling asleep with his new son.
A Beer-Battered Rip Off, Episode 12 (5.9)
During the break that Alan and Lyndsey took during this season, he decided it would be a good idea to sleep with their social-worker, Ms. McMartin. However, when Lyndsey shows up and the two decide that they want to reconcile, Walden immediately freaks out because he knows Alan dumping Ms. McMartin will negatively affect the possibility of adopting Louis. Of course, Walden is right, and Ms. McMartin shows up in the middle of the night to give them a surprise evaluation which ends poorly. To try and smooth things over, Walden lets Ms. McMartin vent about Alan to him... and winds up sleeping with her himself.