She got dumped and she's very sad.
Animals, as well as humans, are saddened by the deaths of their friends.
Don’t be sad. Your Japanese is good enough for now. Just don’t stop learning and you’ll improve little by little.
This word consists of kanji with hiragana attached. Because the hiragana ends with an う sound, you know this word is a verb. The kanji itself means sad so the verb form of that is to be sad. Boohoo.
If you're going to be sad about something right now, it will be kana (かな). Don't use kana when you're trying to learn kanji! You'll be sad forever if you're stuck using kana your whole life, so don't let that habit start now, friend.