Tear Jerker: When Jenna sees Matty kissing another girl in the hot tub. Then one season later when Jake sees Jenna and Matty kissing in her bed. The look on their faces in both scenarios gets you.
Jenna singing the lullaby to her mom can definitely count as one of the (if not the) biggest tearjerking moments in the series thus far.
Sadie crying to her mom about how self-conscious she is about her weight.
The Woobie: Jenna, and to a certain degree, Lissa.
It's hard not to feel bad for Lacey after the whole school reads Jenna's blog and starts to call her nonstop with hostile words. Could be Jerkass Woobie for some, especially considering she really should have known better than to make it open for the public to read and just assume that nobody from her school would ever come across it.