The reason why Head knows all this is because Dick and Heart were literally part of him. Head beholds Henry's brain and therefore the awareness of Henry's urges and feelings. And Head knows Victor's behaviors. So he knows that Victor never understood Henry's heart. And so he knows that Victor isn't able to find Heart so easily.
Also, I think that Henry might've loved Victor but Victor's obsession (especially with his looks) made him feel trapped and maybe even lonely. That's why he tried to find love in other ways.
The reason why Head knows all this is because Dick and Heart were literally part of him. Head beholds Henry's brain and therefore the awareness of Henry's urges and feelings. And Head knows Victor's behaviors.
So he knows that Victor never understood Henry's heart. And so he knows that Victor isn't able to find Heart so easily.
Also, I think that Henry might've loved Victor but Victor's obsession (especially with his looks) made him feel trapped and maybe even lonely. That's why he tried to find love in other ways.