Cloud barely flinches when pulling and kissing Tifa, he's visibly hurt when Aerith denies talking about Zack and he's all flustered after holding her hand that he can't even look at her.
It could mean a variety of things: it could mean
absolutely nothing, it could mean poor cutscene direction on Square's side, it could mean different girls provoke different reactions, or it could mean First Class Soldier
Cloud kissed Tifa while
Cloud (
Cloud, you know, the one she's trying to find?) held Aerith's hand (which is pretty much their entire dynamic since Remake Part 1).
Who knows.
Regardless of OG arguments, why would an author of the remake games create two books, one focused on Tifa and Aerith's past, that very explicitly tells you the kind of love Tifa had for cloud and even retcons a bit of OG with them being close as toddlers and then he starts to distance himself and then right before Rebirth put out a book that says Cloud wanted to be Special for Tifa?
If they fell completely in love and openly declared it, her death wouldn't feel as impactful.
Again, read the Lyrics of Hollow and NPTK.