I keep a stash of tissues next to my bookshelf and a running mental list of books that will absolutely wreck me, and a lot of those are romances tangled up with illness. If you want a classic that punches straight to the heart, 'The Fault in Our Stars' is the first name that comes to my lips — it's sharp, funny, and honest about mortality in a way that still makes me tear up on re-reads. The characters are so alive that the sadness lands harder because you feel like you're losing friends.
Another one that always gets me is 'A Walk to Remember' — simple, sweet, and devastating. The faith-and-first-love angle makes it feel like a quiet hymn: not showy, but it plants a slow ache that grows until the last page. For slightly different vibes, 'Everything, Everything' pairs a cage-like illness with a yearning for normal teenage love, so it mixes claustrophobia and longing in a way that left me breathless. If you like something gritty and morally thorny, 'Me Before You' deals with life after tragedy and makes you wrestle with love versus autonomy; it's messy and will make you argue with the book out loud.
I also keep recommending 'Five Feet Apart' for its YA, clinical-cute energy — two people forced apart by cystic fibrosis who try to create intimacy despite rules. And if you want something that lingers like a bruise, 'The Notebook' handles love and dementia with scenes that will make you clutch at the pages. Trigger-warning note: several of these feature heavy topics — assisted decisions, terminal illness, loss — so I try to warn friends before we read them together. For me, these books are a mix of sobbing and gratitude; they remind me how fragile time is and why stolen moments matter.