Fourteen FULL and sparsely illustrated pages later, we're still no closer to solving this mystery wrapped in an enigma that was first presented to us, by the Original Poster. On the other hand, LJones41 did say that:
This "drifting" theory, though ... upon closer scrutiny, it doesn't seem to hold up. But it's the best lead we've had, so far.
Chakotay NEVER HAD the opportunity to choose between Janeway and Seven, considering that Janeway never gave him the opportunity to choose. Come to think of it, neither did Seven. She and Chakotay merely drifted into a relationship.
This "drifting" theory, though ... upon closer scrutiny, it doesn't seem to hold up. But it's the best lead we've had, so far.