there's no dates so my bad if this doesn't work out, but emma didn't leave boston/return to bar harbor until 2018 and was in boston steadily until 2013 when she decided to travel more and it became more of an "i have my stuff here" situation. but! she very easily could have been doing secretarial duties at his publisher assuming they were in boston, yeah? regular run-ins through technology and during in-person meetings, got to talking, etc and struck up a casual friendship?