Romantic dinner in Inner harbor baltimore
Sadly, you've got three mutually exclusive things -- Inner harbor, romance and crabs.
For Inner harbor recs --- well, ok, there are none. Maybe Blue Sea Grill or Ruth's Chris.
For romance, go to Federal Hill and hit Bicycle or Corks.
For crabs the nearest decent place is probably Obryckis.
Heh, actually four things: good food, inner harbor, romance, and crabs.
Given some compromises, I'm going to throw the Oceanaire out there as a possible suggestion. It's in Harbor East, which has a nice view of the harbor as well as being a very short walk to the actual 'Inner Harbor'. It is, in my opinion, a very luxurious setting with a nice romantic ambiance (especially if you ask to be sat in the section away from the bar). It has crabs in a sense: crab cakes and soups and often specials involving crabs in some way. However I don't they have just crabs to beat and break open.
I'll be honest though, I've been to two Oceanaires (one here and one in MN). The food at the Baltimore one did not impress me. Other hounders have pointed out positive experiences, and because my experience at the MN branch was actually acceptable, I may believe it was more fluke than anything else.
Oceanaire Seafood Room
801 Aliceanna Street, Baltimore, MD 21202
I'll throw it out there again. Pisces (Hyatt Regency Baltimore) has a breath-taking view and is incredibly romantic. I am veggie, so I can't comment on the seafood, but it has pretty good reviews on Yelp (http://www.yelp.com/biz/pisces-baltimore). The last thread where someone reported back on her visit was also pretty positive. Pretty darn expensive, though.
300 Light St, Baltimore, MD 21202