In 1366, Chaucer married Philippa de Roet, a lady-in-waiting to King Edward's wife, Queen Philippa of Hainault. Their first child, a son named Thomas, was born around the following year. (Thomas also went on to have a successful career at court, serving as Chief Butler of England and Speaker for the House of Commons.) The historical record is unclear on exactly how many children Chaucer and his wife had. He definitely had a second son named Lewis, who probably died in childhood, and possibly two daughters: Elizabeth, who became a nun, and Agnes, who became a lady-in-waiting.
In 1367, Chaucer received his first official appointment to the royal court, as a valet - later a squire - in the household of King Edward III. He became close with John of Gaunt, the third surviving son of Edward III. John of Gaunt was a powerful figure in English politics over the next few decades and became Chaucer's political patron. As John of Gaunt's fortunes rose, so did Chaucer's. Fortunately for Chaucer, John of Gaunt had big plans for himself. Chaucer's first major poetical work, The Book of the Duchess, was an elegy written for John of Gaunt's late wife, Blanche, Duchess of Lancaster.
Chaucer traveled often to France and Italy to do business for the King (including, in 1370, a second military tour in France under the command of John of Gaunt). During his travels, he read French and Italian poetry. The poems impressed him, particularly the works of Boccaccio. Up to that point, English poetry was largely modeled after poetry of the French. It didn't have its own style or traditions that could be identified as uniquely English. Chaucer's own early works were either English translations of French poems, or near copies of the French style. As his day job exposed him to Europe's literature, however, Chaucer started experimenting with his own literary style.
King Edward III died in 1377 and his grandson, Richard II, took the throne. This was a good thing for Chaucer. Richard II was close to his uncle, John of Gaunt. Under Richard II's reign, John of Gaunt rose to become one of the wealthiest and most powerful men in England.