Towards the end of season seven Jaime begins to see Cersei as the crazy tyrant that she is. Cersei is willing to betray anyone to hold on to her power. As Cersei suggests that she may very well have Jaime executed, he immediately leaves King's Landing. He changes out of his armor and puts on simpler clothes, suggesting that he may be trying to escape as far away as possible. It would not be enough for Jaime to simply leave and come back.
Jaime will have to leave forever and go someplace very far away to escape Cersei. If he comes back I am sure Cersei will have Jaime killed.
