No and it's interesting how both sides will try to use that info to their advantage. Clotis say... what you just said, Cleriths say "She wasn't having a romantic relationship with Barret or anyone else in Avalanche."
There is a reason I bring up Denzel so much, because he is a major distinction. When AVALANCHE was holed up together, Marlene was Barret's daughter. Not Barret and, just Barret. In constrast, Denzel is linked to both Cloud and Tifa, who get compared with his biological parents on several occasions.
By the same token, AVALANCHE was sequestered together out of necessity, given their war against ShinRa. But Cloud post FF7 had no such necessity. He wanted Tifa to be by his side, wanted her to be with him. And it's more than just them living together. That's another major problem with the Clerith argumentative style I have- context means nothing to them. They keep taking the disputed bits and looking at them without considering what they mean in relation to everything else. They keep thinking of all arguments as silver bullets, able to prove or disprove the pairing on their own, and they take pride when the prove that a foe's argument isn't silver (and ignore when one of theirs is a blank), when in reality, their foes are firing up the Minigun of facts, to get a spread of arguments creating a bombardment of the evidence.
It's not JUST that they live together. It's that they live together, raise two children, one of whom is unquestionably 'theirs' together, the man asked the woman- in a roundabout way- to move in with him, the woman is an important woman to the man and the mother of their family, the woman sees the man as like a young father and their kids as his kids, they have spoken of their mutual feelings to each other, etc. etc. etc. etc.
When you take it all together, the conclusion becomes rather inescapable, provided you're being remotely logical.
And Balth, that's a sledgehammer clue.
(don't ask 
That's why they still are hung up on that CLERITH MUST BE CANON. They can't admit they were wrong, and after all they have said and done. It just keeps going.
