If Lulu knew, even after his death, that Chappu was going to propose to her, it must've made it much more harder for her to lose him. So, I would consider them engaged as well.
Yeah so she just didn't want Chappu to be replaced, and was tired of Wakka trying to bring him back. (She was a little cold then eh?) But after Guadosalam, I think Tidus and Lulu became a lot closer.
