If he's so content to live with the relationship completely sans romance of any kind, why is he concerned about you dating? And, you clearly had to become ok with him dating, even though he's clearly unhappy, why is that something he is afraid of being "blindsided" by?
Without going way into mindreading here, I think it's relatively safe to say that he does want to want you romantically. It's a sign of someone very lost and confused and thinks he can control his desires. Maybe he can. Maybe my husband can, too.
