Not so. Sure, there's been speculation, but nothing PROVEN. The thing is, even within the universe of Democratic voters who would otherwise support Hillary, there are undoubtedly a fair number who are not ready for a PROVEN lesbian POTUS.
And, while that number might not be enough to lose her the nomination, it would absolutely KILL her chances in a general election.
Bump for later read
this rumor the LA Times is supposedly sitting on is one I never heard in this specific form before.
To me, that means that there has been some sort of speculation about this purported sexual issue in the past. Obama hasn't been the subject of scrutiny long enough for that to be true - most of the 'scandal' speculation about him has been related to the question of whether he was a Muslim at some point in his life. On the other hand, there have been rumors - especially on the right - about Hillary's lesbianism since the early 1990s. (Also about her alleged affair with Vince Foster, and that Web Hubbell is Chelsea's father, but I digress....)
To me, that strongly suggests this is about Hillary, and that it's a lesbian relationship.