She was the daughter of John N. Maffitt and Ann Carnick Maffitt.

She was the second wife of Mirabeau Buonaparte Lamar, second President of the Republic of Texas from 1838 to 1841.

They met while visiting the home of a mutual friend, Mrs. Sophy Roberts Settle of Mobile and New Orleans. Mrs. Settle was the daughter of Lamar's friend and mentor, Dr. Willis Roberts.

In February 1851, Henrietta Maffit married Mirabeau Lamar in New Orleans, Louisiana.

They were the parents of one child, Loretto Evalina Lamar, born 1853 at Macon, Georgia.

According to contemporaneous news accounts Henrietta's mother, Ann Carnie Maffitt, divorced her husband over his itinerant lifestyle and moved the family to Galveston, Texas where she opened a boarding house and later a fashionable hotel. Henrietta was the twin sister of Caroline Matilda, who married Judge Robert D. Johnson of Galveston, Texas. Henrietta and her sisters were known for their beauty and intellect. Her youngest brother, Commander John Newland Maffitt, was named after their father and raised in North Carolina by an uncle after their parents separated.

She is best known for the poem Lamar wrote to her during their courtship:

O, lady, if the Stars so bright,

Were diamond worlds bequeath'd to me,

I would resign them all this night,

To frame one welcome lay to thee;

For thou art dearer to my heart,

Than all the gems of earth and sky;

And he who sings thee as thou art

May boast a song that cannot die,

But how shall I the task assay?

Can I rejoin the tuneful throng,

Since Beauty has withdrawn its ray

The only light that kindles song?

No, no — my harp in darkness bound,

Can never more my soul beguile;

Its spirit fled when woman frown'd,

Nor hopes for her returning smile.

Then blame me not — my skill is gone

I have no worthy song to give;

But thou shalt be my favorite one,

To love and worship whilst I live;

Whate'er betides — where'er I roam,

Thine Angel image I will bear

Upon my heart, as on a stone,

In deathless beauty sculptur'd there.