>>3
2d are comprised of drawings or pixels, right?
Physically yes but mentally, they represent more than just that. It's more than human nature to assign connotations and feelings to everything real or fake. In this case, the fake drawing, represents a woman, possibly a woman of their dreams with or without flaws, every person is different. The connotations associated with the image blend with the imagination to create feelings of "love" or more often the case, erotic arousal.
Just like how real life porn can get someone hard despite them never being able to feel, talk to, have, or love them, the same applies for the 2D.
This is kind of strictly talking from the porn perspective though as it's easy to get aroused based on what images represent and mix that with our imagination. I guess waifus would be an extreme case of this combined with other factors such as not being able to get a girl in real, having very high standards, having no self confidence, or that as said earlier, the waifu in question is everything they've ever wanted in a female but can't replicate that in real life.
That's how I see it. People can refute or support my claims. I encourage it.