Mercury is essentially alone in an unknown world, fighting for her very soul, and separated from friends and family alike. Her only contact is to scry on her loved ones at home and communicate with them via morse code. Despite not having any substantial contact with them for month, her friends still throw a party for her at her birthday so she can attend at least look at her friend having a good time on her behalf.
As of DKA: Family Matters chapter, the complicated relationship of Tiger, Ami and Mrs. Mizuno is finally resolved to everyone's satisfaction. Namely - Tiger is now oficially Ami's 'older and bolder sibling' accepted by her Mom and engaging in traditional older sibling behavior. Awwwww!