So is Finn's marriage proposal just his way of trying to give his future some meaning? Robbed of following daddy's path, might he just be clinging to something else? Or, perhaps not. Finn has to really look inside himself, searching for the thing that makes him special, and he feels that Rachel is that thing. Which is certainly endearing. Perhaps they are too young, but Finn's desire to be with Rachel comes from a genuine place, and is sincere. As to whether Rachel is ready to commit to him in that way, well, that remains to be seen. But since this is television, and there is at least one more season left for the pair, she'll probably say no.
Glee doesn't seem to disparage military service in "Yes/No," but it does discourage it for the character of Finn. It's certainly not a decision to be taken lightly, and one that isn't right for most people. Hopefully no one will be offended by this scene of talking the young man out of enlisting. No offense seems intended, nor warranted.Instead, it calls attention to the harsh truth, less often spoken of, about our troops. Which is something worth exploring.
Mercedes also struggles with her romantic notions in "Yes/No." Pursued by Sam (Chord Overstreet), Mercedes insists that what she has with him is just a summer fling, and she is over him, happy now with Shane (Lamarcus Tinker). But in "The First Time I Ever Saw Your Face," her thoughts go to Sam, not Shane. Does this mean that Sam is the one that she wants (hehe)? Probably, since Sam is a more central character, and unfortunately, despite Tinker's other respectable credits (Cougar Town and Friday Night Lights) before coming to Glee, he has been used practically not at all. Mercedes may choose Sam, but the real crime here is Tinker being wasted on Glee.
If you didn't understand the "hehe" in the preceding paragraph, think of the lyrics in Grease. This is made a more obvious link by the rendition of "Summer Nights" Sam and Mercedes perform in "Yes/No." One wishes Glee took more liberties with the words to apply the number to the couple's actual doings. What is present, instead, is a version extremely true to the movie it comes from, with camera shots echoing the original. It's cool, and a well done homage, but it doesn't really give fans any insight into what actually happens between the two off screen, and that is something many long to see.