[Formendacil]

Yup, you're wrong.

Ioreth was an old, single woman in Minas Tirith. Eligible, but not Eomer-marrying material.

Eomer's wife was Lothiriel (with a ' over the "o", which I am too lazy to try and find the code to), the daughter and youngest child of Imrahil, Prince of Dol Amroth. Other than general family history, nothing is known about her.