I wasn't too sure what to make of this episode at first, in middle, or until near end.
At the very end is where this episode shines, when Ted and Marshall are being vulnerable about wanting to do what the other is doing with their free time. Marshall is maturing and doing more adult-like activities with fiancee, like hosting wine-tasting nights. Ted is going to clubs and picking up women with his single friend Barney. This reminded me more of "gift of the Magi" because Ted wants to meet someone so that he can enjoy his friend's company via adult-like activities, like wine-tasting.
And isn't true that the dynamics change in groups when relationships progress? When your friends are getting married and you see less and less of them. An encouragement has been that in Christian culture (and I use that phrase with a definitive representation in mind) the gospel transcends relationship status. A married couple may have fewer things in common with their single friend, but they can still just as much enjoy each others' company when their conversations point them to Christ.
Another nugget from this episode: Don't try and force yourself to be someone you are not. That's not to say "don't mature", it's saying don't let others dictate your progression.