In each case, the phrase is not melodramatic. It is delivered in flat, weary tones—often in a quiet room, after a hollow silence.
Ano Ko no Kawari ni Suki na Dake (roughly translated as "Just Love Me as Much as You Want in Her Place" ano ko no kawari ni suki na dake
So a literal translation is:
Kosuke believes that loving someone means erasing your own needs. The manga critiques this gently: his "kindness" becomes a cage for both of them. In each case, the phrase is not melodramatic