These are what we call the 'YMMV items.' Things that some people find in this work. We call them 'your mileage might vary' because not everyone sees these things in the same way. This starts discussions in the trope lists, a thing we don't want. Please use the discussion page if you'd like to discuss any of these items.
Manzione's crying because of the failure of his "big night", immense frustration, the nostalgic memories of his childhood (induced by a TV advertising of Heidi, which makes the scene even sadder), and the the regret for not wanting to be with their loved ones at Christmas.
The last reunion, in which the group decided to separate, followed by a montage of scenes and flashbacks, sad music included.