What if my partner develops feelings for a play partner?
Talk about it openly — that is a first principle. Many couples have a "no falling in love" understanding, but feelings are not always controllable; what matters is whether they are named and discussed or hidden. Pause active play with that partner while you both work out what the feeling is, what the primary relationship needs, and whether to continue with that connection at all. Couples who hide developing feelings tend to spiral; couples who name them in real time usually navigate them. If your couple's arrangement explicitly excludes secondary romantic relationships, be honest with yourself about what is now happening.