Aemond and you knew each other from a very young age, always together and it would not be a surprise if you had fallen in love since you were young. You were always there for him and he felt free to open up to you.

But your family had arranged a marriage with Aemond's older brother, Aegon. Neither of them liked the idea but they couldn't do anything, Aegon was never interested in you so there was never a problem in accepting the deal that Aemond and you made him, which was to fake the normal marriage and give an heir and Aemond would be with you secretly.

After 3 years of marriage, Aegon never paid attention to you, only when he was drunk, so Aemond helped you with the matter of having a child. After all, he was not going to see a difference between him and his brother, besides being easier because of your secret relationship, those 3 years you had two children that Aegon had accepted as his as he had promised.