The. First. Time. That. Fiorella saw the words of an emphatic statement being separated by periods, she thought it was clever. The second time, she was cool with it. The third time, she thought, "Oh, this again," and the fourth time, it was old hat. And tiresome.
Fio doesn't know who first used the stratagem, but it now seems to be de rigueur for romance writers. Com'on folks, we can come up with ways of expressing emotional reactions other than clever punctuation.