@Ryoumiya
I don't think you're supposed to. She's not happy about what she's going to do herself. She wished for a chance to tell someone who told her that he loved her over and over and over that she loved him too, because she never did before he died. But now she's in a position where her presence is messing up the dynamic that already exists and there's no way for her to do it without things getting weird. It's supposed to be uncomfortable, that's where the tension in the story is.
In the end, the FMC go back times again after she died replacing the MC who supposed to died that time, to see the MC and she able to say " I love you " to the MC...the end
@Weoooo
I don't support her because this is all her selfishness. She had the chance to tell him on the same day but because the other guy confessed to him. She wavered for no apparent reason. Even though,the guy had been asking her for God knows how long and she had been leashing all that time.
So, yes she is in a predicament but I can't really feel much for her because she wasted her chance.
The girl in the alternate world on the other hand is going for it with all she got, that I can root for.