Materials expand under heat. Couples expand under stress. The space isn't rejection—it's the physics required to prevent structural damage. The relationship contracts back as the temperature drops.
In a relationship, you and your partner play driver and engine in turns. Both burn energy. Asking for space isn't withdrawal—it's the engine cooling down so it can keep running.
Electrons repel when forced too close—an electrostatic response to invasion of space. Couples do the same thing, and the way the system releases that pressure decides whether the bond holds.