Shouldnt it be the witch of heart the one who manipulated relationships tho??

Blood and Heart have some Overlap- Bonds and Feelings aren’t the same, but they tend to go hand in hand. If you change someone’s bond with someone else but they still feel the same about them, it could lead to a painful break-up, whereas changing someone’s Feelings would lead to a more mutual break-up, but in both cases, the result is the same. So relationships are both Heart and Blood based.