A painting simply named "Portrait of a Young Woman" that may possibly depict Catherine.

Catherine arrived at court for her new job in household of the queen before the new queen, Anne of Cleves, did. Two years before, Henry VIII's third wife, Jane Seymour, had passed, leading to a search for a new bride to take her place. German Anne of Cleves was chosen. Henry went disguised to meet her for the first time on her journey to England, but Anne didn't know the disguised man was Henry, leading to her paying him very little attention which soured Henry's first impression of her. Henry also found Anne's appearance quite plain, and attempted to find a away out of the marriage before it even happened, which was impossible. After marrying, the union was never consummated, and only a few months later an annulment was sought. Anne was subjected to countless insults of her appearance in court in order to make a case for the annulment.

While this was happening, Catherine was adjusting to her new life at court. She began a flirtation with Thomas Culpeper during the winter, with Culpeper pursuing her far more than she did he. When he moved onto another lady, she apparently broke down into tears, not used to such rejection. Culpeper was not the only one who had noticed the pretty young Catherine, now only 17 or 18, at court, however. Even before the arrival of Anne of Cleves, Henry VIII flirted with the teenager, though at this stage with his bride on her way, not much came of the relationship. After Henry met and disliked his new wife, he sought to gain an actual relationship with Catherine. He began to court her during his marriage to Anne, though it is unknown if the relationship was sexual at that stage or just courting. With the king's impending divorce on the horizon, Catherine was solidified as Anne's replacement.

The then 49 year old Henry VIII married his teenage bride on July 28th, 1540. The first months of the marriage were seemingly happy, but soon Catherine's eyes went wandering back to Thomas Culpeper, who once again took an interest in her. While on progress, this flirtation would turn to more as Catherine asked her favorite lady in waiting, Jane Boleyn otherwise known as Lady Rochford, to help her arrange rendezvous with Culpeper. Lady Rochford would map out routes to take in the various houses they stayed in during the progress, and Culpeper would secretly meet with the queen at night. According to all involved, the two would do nothing but talk all night, and no intercourse or even kissing was had, however Culpeper would later say during the trial that he did intend to sleep with the queen. Had it gone on longer, the relationship may have evolved into a full affair.