Sandy Lam's 2012 album, GAIA, had a lot of very controversial topics, including fatal love and self-destruction. The lead single is a fierce blast at humankind as a whole for being so reckless with Earth, with each other, with our responsibility to explore the Universe... Very powerful song.
KOKIA's 2015 album, I found you, is strictly about how she changed after marrying, and what the profound love she shares with her husband has taught her about hope, pain, and kindness. Also, I should mention, it can be a very sad, reflective album at points, if you have struggled with depression. Dear Armstrong is a little heartbreaking for anyone who wants so much to see the world as a beautiful place.
Also worth noting, KOKIA's 2013 album, Where to go my love? was about the nature of music itself. The title is a colloquial question to music itself, as in, "What shall music and I do together this time?"
Apart from Asian artists, Antony Hegarty (Antony and the Johnsons) has written dozens and dozens of songs about environmentalism, death, self-destruction. All are very hard to grasp, very emotional, so I recommend keeping your listening of him to a minimum. I listened to Antony religiously for several months and everyone thought I was suicidal.