Wow, what a biazarro but interesting question.
First of all, you sorta left this wide open without much context. Are we dating this person for 6 months? Or married to them for 60 years? I'll assume it's a more long-lasting relationship, because otherwise the obvious answer is touch/sex...otherwise, you can get pretty much the same effect from any number of friends (well maybe not taste) that you would from some 6 month fling or crush.
OK, so assuming really long term...
Taste - no.
Smell - of course not.
Touch - tempting but if you can't see or hear anything this doesn't seem like it would be especially appealing. And even less appealing as time went on.
Hear - that's an interesting one, because the conversation piece like you mentioned is pretty damn important. But even without hearing there are ways to pretty easily communicate with someone if you can...
See - so this would be my answer. The easiest & best way to appreciate stuff around us, whether it's nature or art or people is to be able to *see* it.