Early morning research is causing Gabriel extreme anxiety and he is anything but cool, calm, and collected; Olivia's sudden appearance in his office does not improve matters one bit. (Small spoilers for 'Deceptions'.)
He had deserted and been deserted so many times that he believed it was an innate thing to do. He never pondered on the fact that maybe it was worth staying, that he was worth staying for. And as he watched her, he let it set in that finally he could have her, and she would stay. Gabriel/Olivia.