In the Twin Paradox scenario, where one twin stays on Earth (the "stationary twin") while the other twin travels at high speed and then returns (the "traveling twin"), the traveling twin will indeed experience less time passing compared to the stationary twin. However, it is important to note that this is not a symmetrical situation, and the paradox is resolved by considering the difference in inertial frames of reference.
From the perspective of the stationary twin, the traveling twin undergoes a period of acceleration and deceleration to change direction at the turnaround point. This acceleration introduces a difference in the experience of time between the two twins. According to special relativity, the twin who undergoes acceleration experiences time passing more slowly compared to the twin in an inertial frame of reference.
So, in the scenario you mentioned, where the traveling twin has aged 2 years less when returning to Earth compared to the stationary twin, it does not mean they aged 1 year less on each leg of the trip. The traveling twin experiences less time passing due to the acceleration involved during the turnaround. This time dilation effect is consistent with the principles of special relativity and does not violate any fundamental laws of physics.
It's worth noting that the Twin Paradox is often used as a thought experiment to illustrate the concepts of time dilation and relativity. In practical situations, where one twin accelerates and changes direction, the resolution of the paradox becomes clear when considering the differing frames of reference and the effects of acceleration.