DonIago, it took the Doctor shortly over a month to figure out how to separate the two of these individuals, by which time he was already completely assimilated into and accepted by the crew except for Kes who didn't want to be sexually pressured by this man who was both already her lover and thementor who spent hours every week psychically penetrating her.
Notice how Janeway cites all of Tuvok and Neeix's family connections even if Tuvoks family already thinks that he's dead and the wife is already interviewing new suitors so that she doesn't die form pon far, unless the custom is that she dies from pon far because her life mate is dead... In which case Tuvok should have tried to get home faster, and when his wife started dying on the other side of the Galaxy, in concert he should have allowed himself to die with her, other wise he's a just being a punk ass bitch to a good woman.
If Tuvix had moved on and took a real girlfriend from some other crewman who championed his cause in direct opposition of Kes, cupping his sack and announcing loudly to the world This is mine! This is where my babies come from! Janeway would have caved. It was only his fixation of getting back into Kes' bedroom suite that fixed his little red wagon by leaving him disconnected emotionally from a lover/life partner who could have claimed him... If Tuvix had slipped a quickie wedding under the wire at the 28 day mark if he had been following the doctors moth long progression into killing him, Janeway would not have had the balls to follow though to break up a real family.
"Ensign Jenkins is pregnant with my Child Kathryn, do you really want to face that pointy eared, whiskered little minx every day for the rest of your life knowing that you murdered his father because some little girl is having a temper tantrum?"
So Kes is still the problem.
Tuvix didn't fully integrate and completely creating a life for himself on Voyager because he was waiting for Kes to get over her homicidal feelings for his sick lust for her and open her heart up to his proposal that they should be together forever as she was orchestrating his death.