"Life After You" by Daughtry. It's about a guy who broke up with his significant other and is struggling to find joy without them, so he's returning to see them again. I dunno why, especially since I've never been in a romantic relationship since I first heard the song, but it really gets to me. Especially the lines in the chorus, "I'm thinkin' that all that still matters is nothin' but laughter. After the life we been through..."
Also, depending on how I'm feeling at the time, "Lifelight" from Super Smash Bros. Ultimate can make me cry. It's probably not the intended message, but I feel like the song is about overcoming depression.