Modern stories use in-game texting to send funny memes, share plans, or introduce conflict, such as receiving a message from a rival while with a current partner. How Texting Enlivened the Modern Romantic Comedy
For more specific information on "kuwari mobi" relationships and romantic storylines, it would be helpful to have a clearer definition or context of the term. Japanese media is incredibly diverse, and terms can have very different meanings or connotations based on the context in which they are used.
A relationship that transforms both parties through movement, metamorphosis, or mutable identities. Think: shape-shifter x mortal, time-traveler x fixed-timer, AI gaining emotion x human teacher, wanderer x homebody.