Miss Kelly was the only one who mentioned the possibility of her coming home on holidays. No one else mentioned it. (1.215)
When Eilis decides to leave Ireland, she does so assuming that she'll never be able to return to her childhood home. To be honest, it was a lot harder to globe-trot back when you couldn't just take an Uber to an airport.
Rose was thirty now, and since it was obvious that their mother could never be left to live alone [...] Rose would not be able to marry. (1.222)
And not just that—it also means that Rose will never be able to leave home. In many ways, Rose is sacrificing herself for her sister, bearing the burden of her mother's care so Eilis can move on to a better life. This is a selfless act, and not one that Eilis will ever forget.
His saying that at the beginning he would have done anything to go home was strange. He had said nothing about this in his letters. (1.305)
Although Eilis has no idea how to handle her feelings of homesickness, she takes some comfort in the knowledge that her brother Jack went through similar emotions. Even with this, however, she struggles to figure out how to dig herself out of the hole of depression.
All of this came to her like a terrible weight and she felt for a second that she was going to cry. (2.55)
This is what happens when Eilis first receives letters from back home. Instead of making her feel better, they just remind her of everything that she's left behind. What a bummer.
She was nobody here. It was not just that she had no friends and family; it was rather that she was a ghost in this room, on the streets on the way to work. (2.56)
At this point in the novel, Eilis still hasn't built up a social support system to help her get through these hard times. Even worse than that, however, she feels like no one notices her, that no one understands her. If we were in her position, we'd be praying for teleportation powers every night before we went to bed.
She considered writing to him now asking him if he too had felt like this, as though he had been shut away somewhere and was trapped in a place where there was nothing. (2.77)
At her lowest point, Eilis feels like she's in exile from her homeland. There's nothing for her here in America except for loneliness, and she'd give anything to see the craggy coast of Ireland once again. But here's the thing about hitting rock bottom, folks—once you've reached your lowest point, the only place left to go is up.
Eilis thought, as she sat down with a glass of sherry in her hand, that it could have been a parish hall anywhere in Ireland on the night of concert. (2.239)
Eilis doesn't only get spiritual fulfilment from Father Flood's church—she gets a community. Although she may be far away from home, being among so many rowdy Irishmen gives her a small but powerful connection to her home country. This makes a huge difference.
Eilis loved her room, loved putting her books at the table opposite the window when she came in at night and [...] spending an hour [...] looking over the lecture notes. (3.156)
It takes a long time, but Eilis eventually feels at home in Mrs. Kehoe's boarding house. Of course, it helps that she scores the best room in the building, a secluded basement perfect for late-night studying or—uh—other late-night activities. Either way, it's a big step for Eilis that she's finally looking at Brooklyn as a home, rather than a prison.
Her mother showed Eilis Rose's bedroom [...] She had left everything, she said, exactly as it was, including all of Rose's clothes in the wardrobe and in the chest of drawers. (4.1)
That's... a little creepy. We shouldn't come down too hard on Mrs. Lacey, however, as losing a child is a pain that we can't even fathom—a little bit of irrationality is par for the course in this context. Still, we're not sure if having an ever-present shrine to your deceased daughter is the most effective way to make peace with her memory.
She was glad she did not have to write now from her bedroom, which seemed empty of life, which almost frightened her in how little it meant to her. (4.11)
Although Eilis loves her family and friends in Ireland, returning there after Rose's death forces her to admit that it's not her home anymore. For better or for worse, that place is in her past now—her real home is in Brooklyn, New York. Naturally, this is an incredibly bittersweet moment for her.