This is a two-fold answer, the one the reader feels cathartically, and the one the reader feels cathartically under the same circumstances that Eveline had. It is hard to determine whether it was "the mistake of her life", because her life, as she knew it, was no life to begin with.
Eveline had not known freedom, love, belonging, peace, comfort, satisfaction, a fullfilled womanhood, nor that feeling of being special that all women love to feel when we have spent time and efforts sacrificing for others.
She, instead, was expected to sacrifice, and was demaded to give up herself. Having to change that would have been the end of the world as she knew it, and a very huge change of pace. In the end, she could only live in one world: The one that was set out for her from the beginning. The rest, would be just another dream.
In the short story "Eveline" from the collection Dubliners by Irish author James Joyce - a young girl who has lost her mother is paralysed by duty and temperament into accepting the situation that she is left with. However, we can all relate to the story in different ways - which is one of the things that makes it a good story. To my way of thinking, I feel that Eveline also might have regretted it if she Had gone! For example, although she is burdened by her sisterly/daughterly responsibilities at home, she also loves her family and seems settled in her neighborhood - suppose it hadn't worked out with her new love? If the match wasn't compatible and she was miserable - she would have been stranded thousands of miles across the globe,perhaps with a baby, lonely and unable to get home.
In James Joyce's "Eveline" the reader encounters a character representative of the abused child or wife who is conditioned to accept the state in which she/he lives. In addition, Eveline loves her little brother dearly, and, having raised him as a mother since the parent has died, Eveline is torn between her own desire to have a better life and a sense of obligation to her sibling who is also like her child.
Her moment of indecision with the sailor--whom she does not know all that way anyway--involves this conflict. Ultimately, her love for her brother and fear that he will suffer more abuse from her father makes her sacrifice her personal interests for family. While hers is a tragic choice, Eveline is unselfish in her decision and is to be respected for her love. That she perceives only these two choices is, perhaps, a mistake as she may have had other options other than remaining with the abusive father.