In her eyes momo is literally, a PET. Someone whose dependent on her, cares for her and comforts her, but certainly not a love interest or a “man”. While Momo has attraction to her from the get go (maybe it’s just lust + the situation is interesting but certainly he’s more than willing in the beginning), she sees him as nothing more than a replacement for her dog. The best way to put their relationship in sumire’s eyes is “Business transaction”, where she pays him (food, a place to sleep, etc) in return for his services (listen to her complains, let her hug/cuddle him, etc).