I never liked the Chakotay\Seven romance, either. They had absolutely no chemistry at all. Personally, I thought Chakotay and Janeway would have been a better fit.
I mean I have tried to rationalize it in that in Unity, Chakotay fell for a blonde human Borg girl, Riley Frazier. It is possible that maybe Seven and Chakotay read each other's thoughts like Chakotay and Frazier. But they never explored that at all. And again, there just was no chemistry between the two.
That, and the fact that Chakotay tried to KILL Seven when they first met!
On Seven's end, the love of her life in Uni-matrix Zero, KoroK, could have had more stories, and they could have reunited somehow, with a good script. Would have made more sense.