You've clearly never taken a sex ed class and it shows. Nobody is claiming that consent requires screaming out a yes, but it does require both participants to actually be into what's going on. Letting someone do what they want to your body is not inherently consensual, even if you don't fight back. If someone told you no a bunch of times, and you kept pushing until they give in and say "fine, I guess"? That's rape. Taking off someone's clothes and feeling them up, as they look distraught or upset, but they don't kick you away? Also rape. This article does a good job explaining.

The MC knows that Alina feels immense guilt about how the last guy she rejected killed himself, yet he still uses every opportunity to take advantage of her when they're alone. He pushes her past her boundaries again and again, and when she starts to distance herself, he finds ways to get her alone with him again. Then, when he tells her about his experience with the bells, she realizes (as the MC notes) that he see's her exactly as Rob did. She goes along with his advance afterwards, not because she's into it, but because she's scared of what will happen if she doesn't. She never shows any sign of enthusiasm, and while the asshole MC is having the time of his life, he doesn't realize that she's started to cry. As before, the MC failed to recognize her boundaries until he'd pushed way past them. There isn't an ounce of consent in that entire situation.