Answer:
Assurance
Step-by-step explanation:
Assurance is one of the most common relationship maintenance strategy which involves making commitment to one's partner, and showing support for them in a manner that comforts and emphasizes their willingness to remain faithful in the relationship.
Behaviors such as regularly sending of e-mails and instant messages to stress the intention of wanting their relationship to continue despite the physical distance between them, can be referred to as the relationship maintenance strategy called assurance.