Above all, it doesn't make sense in terms of the plot either.
1. the media are practically aware of all the MC's relationships and a relationship with Willow, for example, would cause a medium to large scandal.
2. while most girls strive for careers in which they can support the protagonist, Willow strives for a career in which she can support children who have gone through similar things as she and her brother.
While the two will definitely stay in touch and probably see each other as often as they possibly can after the plot unfolds, nothing more will come of it.