
Spoiler. Sort of. Read at your own risk.
From the novel, she explains that she 'lied' by abandoning all chances of ever visiting his homeland.
After being captured in her previous life, she overheard gaurds speculating about how they thought Kaid/Helt was bewitched by the MC since he did not wish for her death and instead wanted to send her to a monastary. Therefore, MC thought the citizens would have similar views and would start doubting their new Lord. So, she forced Kaid/Helt to kill her by not even trying to plead her innocence and did not respond when he tried to give her a way out. She even made a ruckus at her execution to make it seem like she was truly evil. How could he not follow through after that public display. She dashed all chances of survival and thus would not be able to visit Kaid/Helt's homeland with him.
Thats why as you read, you can sort of tell Shirley feels guilty and thinks she is always in the wrong since she felt like she forced that kind of ending which burdened Kaid/Helt's heart for 15 years.
Sure everyone dosen't like how he deceived Shirley in her past life but ....... This plot point leads to one of my favourite talks between them. It really made me appreciate other side characters like Caroline more. I can't imagine it any other way. Or maybe there could have been but my imagination and creativity is non-existent. Its so bittersweet. Albeit on the bitter side so might just be my unpopular opinion.
When she said that she lied in chapter 5 what did she mean?