Sexting is not the same as sex, in the sense that bodies are not directly interacting. It is, rather, minds interacting through phones. Just as sex flourishes in conditions of physical safety and respect, so sexting requires a certain degree of emotional safety if it is to work for both parties. When that condition is absent, sexting hurts the relationship.
sexting needs to occur within the wider context of honest, back-and-forth conversation. How does your partner really feel about sexting app? What kinds of sexts are acceptable and what are not? In what circumstances, if any, could pictures or text be shared? Is there a type of communication that feels threatening or just uncomfortable? While it may seem not-fun to have such conversations, their absence can destroy a relationship.
This is especially the case when a partner has past bad experiences—or an insecure attachment style.