3. Barney's Not The Marrying Kind
Barney's a playboy. That is his character. How are we supposed to believe he can commit to a marriage? It would be a huge disservice to the ever-so consistent series to have Barney abandon what shapes his entire personality. I'm not saying Barney doesn't deserve to be married, but ever since his engagement to Robin, we haven't seen that confliction in Barney; he has yet to confront his past demons. When Ted was on the verge of marrying Stella, Barney wanted to admit his feelings to Robin. At the time, Robin was stationed in Tokyo, so Barney had to wait for Robin to fly over before he could make said admission. By the end of the episode, Barney succumbed to temptation and slept with another woman. Why should we believe this won't happen again? Barney has a few skeletons in his closet... and I can't think of a pun to round this out.