I don't have any complaints about relationships as i feel it allows your characters to develop a deeper personal life then you could before. in the shackled hut, a sidebar describes the possible relationships and romances the PCs could have. My group has like the idea of relationships in the past so i like the option in APs. Here's my personal points on them.
Nadya Petska: if all goes well (her son survives the wolf attack) you can have a valuable companion on your team providing much needed wilderness skills if you don't have any and her anger towards witches will be a boon against some of the foes you face. Romance: possibly will be a good match with individuals who can find the patience and effort to warm up to her and establish a romantic relationship. a character to which I could find pairing well with either the witch hunter in the group or another member who can help heal in the wounds in her heart with the loss of her daughter.
Greta: A difficult and unique relationship at best. can provide needed muscle to the PCs while her wolf abilities can aid in tracking down foes. personal thoughts, she would play an excellent NPC for the players as they attempt to slowly convert her from NE to possible CN, CG, or NG alignments. I am creating a sidenote at the end of the adventure in which the PCs found Baba Yaga's library and discover her notes on how she was able to give winter wolves human form in the Howlings district. an arcanist in the group will apply the spell to the Rimepelt allowing her to use it to take human form as long as she wears it. might later give her permanent human form ability as Baba Yaga's gift. Romance: definitely will use a romance to coax her away from evil and begin to grow her a heart at least towards the PC who owns the Rimepelt. Will make children from this union natural werewolves with minor frost resistance.
Ringeirr Malenkov: will not be seeing much of him as he will be taking care of his nephews while their mother is with the group, unless Nadya losses one of her son's to the wolves in which case she will be staying in the village, giving Ringeirr the role of guide and wilderness expert. Romance: only possible if he joins the PCs and i feel he is not interested in romance so any attempt will take a great amount of effort and time.
Solveig Ayrdahl: if you are successful with rescuing Bella, then she will be just a NPC you work with in The Shackled Hut. but in the off chance Bella dies, she could be a valuable healer for the team and a possible romance with a female member of the PCs.
Ecology of winter wolves says that offspring between humans and winter wolves always results in winter wolf children though in the case of humanoid mothers pregnancy is a more difficult ordeal for them if they're outside the Howling District. Honestly I do like the idea of any children conceived being faux werewolves with the winter wolf's immunity to cold and breath weapon but a human siring a winter wolf child does make for interesting role playing and character developement since it fits in real well with the more magical fundamentals of the game and basic folklore.