While Janeway flirted with Chakotay at the beginning of their commanding pairing, she made him eventually understand later, that she was not interested to pursue a relationship with him, Seven started a romance with the 1st Officer, more out of curiosity than by for a real interest for him. Why? Because we never saw what made Seven pass of using a holo-Chakotay as her sample mate in the holodeck to simulate relationships, in "Human Error", to date the real Chakotay in Endgame...
(It would have been interesting to see 1 or 2 episode(s) that bridges this gap, showing why Seven initiated the decision to take the next step; why Chakotay accepted the offer and finally, how they were supposed to become a couple? In fact, in default of appreciating this pairing, we would have been able at least to understand the why, even if this romance doomed to failure* even before having seriously begun!
-> 4 weeks bfore the break-up?!)* I do not see how it could be otherwise in view of their respective expectations (for Seven, to date the holo-Chakotay or the real Chakotay, it remains an experience (surely pleasant) to be lived, as a necessary phase to move forward in the discovery of her individuality and to become fully human. As for Chakotay, to date the young and sexy Seven, soothes his ego and it's a pretty good consolation with regard to his 7 years of forced celibacy ... even if he would never admitted it. But at the end, each will come to his/her senses after this short (but rather pleasant for both) interlude and they will eventually leave friendly -> post-Voyager books written and the only webserie ever been made, completly gave up the idea of Chakotay/Seven!
).
) So why is he so critical about C/7, knowing perfectly that he is the main cause? 
