Am I the only one who absolutely hate the 'deserve' shit? I mean, love isn't about deserving ._.
In a work like FF7 where there's a LT - or supposedly, at least during Disc One - you can build up connections and bonds between the characters, discover their past and how it cements the present and future. But in no way it's about deserving.
For example, speaking of Tifa staying with Cloud when he was a veggie, I personally hated her decision - but I understood it story-wise. I just didn't like that she chose one person over the planet. But, narratively speaking, it shows what Cloud is to her, what he means to her - he means more than everything else combined, something that in the end was highlighted again in the scene under the Highwind. Does it means that she deserves him, because she's able to abandon everything just for him?
You can see, during Disc One, that Aerith becomes very dear to the whole party, that she built a very sweet friendship with Tifa - I remember, I think it was the village before Junon, where they are talking with each other about random stuff. We know she definitely fell in love with Cloud - but with her being abandoned by Zack (sort of), being the last Cetra and shit, does it mean that she deserves Cloud because of all the troubles she had in her life?
In the end, it's not about deserving; love isn't a fair game. And the real choice is Cloud's, a choice that stems from when he was a kid up until now, minus Disc One.
Also, I have to agree that their childhood connection - Cloud and Tifa's - was meant to connect them further, but also to show how fucked up Cloud was, even when he was normal.