Really? Wow, I'm sorry but I was fourteen and I saw it coming since I was eleven.As someone who studied Voyager from a writing aspect (and pitched to it six times), I found the relationship almost as abrupt as Chakotay/Seven.
I think it's easy, afterward, to pick out moments from previous seasons and believe them to be "the beginning", but I honestly don't believe they were intended as groundwork. We could just as easily find moments to set up almost any other pairing, had it happened.
The Tom/B'Elanna relationship (in terms of series character arcs) just really hit me as being from left field.
--Ted