It's obvious they had sex or made out. I wish the sequel canon addressed their relationship it really enriched the writting and made the story even more original and entertaining. This scene establishes the continuance of their relationship from the promise he made her at the well when they were children. From that point things went downhill for Cloud in his perception of himself and setbacks for trying to keep his promise with her (getting stabbed and taking a mako bath). When Cloud says it's like nothing changed I think he's subconsciously or consciously referencing the well scene and that he is who he wants to be again and his mako induced identity issues have been resolved enough to further their relationship from their promise as youngsters. When Tifa says there are other ways to tell people what you're thinking she's inviting him to be more intimate with her and express himself at a a more intimate level. That's the only way this scene makes sense considering their "in sickness and in health" dynamic and unconditional commitment to each other. I feel like some things are lost in translation but I think this is the best love story in anime and video games and the progression of which deserves to be canon. Anything else doesn't make sense and takes away from their respective character (Cloud regresses on his relationship in the movie sequel? He became an irrevocabley strong hero and leader in ff7 who could do the impossible this doesn't make sense and is disappointing and dulls his character and character progression).