Today, on leaving my friend at the cafe, I got her nose.
She insisted I give it back because she'd need it. But I just walked away. It's mine now.
See, the thing is, at least the way I work -- and this seems to reflect other INTPs I know -- affection is paramount. Even in my closest relationships, it's just a question of degrees. Actual overt amorous attachment is so rare that I felt like I was going insane the one time I felt it. And I kind of behaved that way, frankly. Complete personality change.
I think the INTP modus operandi is to keep experimenting with affection, to try to carve out a sense of how he or she actually does feel. What's the shape of this relationship? What if I prod here? How about this? Is this good? Or what if I do this? No, that feels weird. It's like a cat, trying to figure out just the right place to sit.
Once the INTP has actually come to a conclusion, the declaration tends to be pretty straightforward. But there's no sense in rushing it; any uncertainty in the INTP's own mind, and... although if prompted it's likely he or she will go forward with things, out of deference and respect to the obvious affection at hand, which clearly means something, the INTP is going to be a profoundly ambivalent partner. Not knowing, not understanding will eat away at the INTP. And this isn't a field the INTP is good at.
INTPs tend not to screw around. If they're not forthcoming, it's because they don't know themselves. If they're putting off the problem, which is likely, perhaps a nudge or two might spur them into action (whatever their conclusion might be). Too many nudges, though, and you just push them away.
Unless you're confident in gently steering things, best just take any affection at face value. It is what it is, and for what it is it is true and important and precious, and means precisely itself. If anything more develops, you'll be the second to know. The INTP will probably be elated, and eager to share his or her new revelation. Eureka!
I figured it out! I love you! I mean, I really love you! Like, love-love. And here I'll explain in precise detail how this works. What do you think of that! Isn't it neat?!