In a purely romantic relationship, cheating would just be like having a boyfriend who considers himself in love with another girl and he goes and sees her and kisses her and cuddles with her and tells her he loves her.
En una relación puramente romántica, ser infiel sería como tener un novio que esté enamorado de otra chica y vaya a verla y la bese y la acaricie y le diga que la ama.