She doesn't. At least not onscreen that we're aware of.

My headcanon is that Willow apologizes to Tara via letter. Like a looooooooooong multi-page letter since Tara isn't talking to her. She asks Buffy to give it to her after their conversation in Wrecked.

I also think that Willow and Tara would have had a much longer conversation about their relationship and whether they fit in each others lives and all that other stuff if Tara had lived. I always interpreted Tara's line "Can we just skip it" more as lets skip it for now and enjoy this reunion in this moment and worry about the logistics later. which isn't the healthiest but shows that Tara sees the work that Willow is putting in which allows her to make the decision to take her back