Chapter 2 begins by describing the events of the seventh day of creation:
Thus the heavens and the earth were finished, and all the host of them. 2 And on the seventh day God finished his work that he had done, and he rested on the seventh day from all his work that he had done. 3 So God blessed the seventh day and made it holy (וַיְקַדֵּ֖שׁ), because on it God rested from all his work that he had done in creation. (Genesis 2:1-3 ESV)
God blessed the seventh day and made it holy. The word holy is וַיְקַדֵּ֖שׁ which is sometimes translated as consecrated. One element of the meaning is to set apart (Strong's 6942)
For example, when Solomon dedicated the Temple, the offerings were so large the altar could not hold them. So he set apart the middle of the courtyard:
Solomon set the middle area of the courtyard apart to the Lord. It was in front of the Lord’s temple. There Solomon sacrificed burnt offerings. He also sacrificed the fat of the friendship offerings there. He did it there because the bronze altar he had made couldn’t hold it all. It couldn’t hold the burnt offerings, the grain offerings and the fat parts. (2 Chronicles 7:7 NIRV)
The remembrance of the seventh day is that it is to be set apart from the other six days of the week:
“Remember the Sabbath day, to keep it holy. 9 Six days you shall labor, and do all your work, 10 but the seventh day is a Sabbath to the Lord your God. On it you shall not do any work, you, or your son, or your daughter, your male servant, or your female servant, or your livestock, or the sojourner who is within your gates. 11 For in six days the Lord made heaven and earth, the sea, and all that is in them, and rested on the seventh day. Therefore the Lord blessed the Sabbath day and made it holy. (Exodus 20:8-11 ESV)
Whether or not it was intended, the Chapter divisions in Genesis 1 and 2 follow the command to set apart the seventh day. The first six days are found in Genesis 1 and the seventh day is found in Genesis 2.
If this was intentional, then it was to apply the command to the extent possible. In other words, a division was deemed necessary to ensure the written word of the seventh day was truly set apart from the first six days. If it was unintentional then it can be seen as done through inspiration from the Holy Spirit, who understood the significance of having the division.
Now one might question why the seven day was not given a separate chapter and truly set it apart. The answer can be seen in what follows. Certain creation events are recounted but from the perspective of the LORD God and the first man and woman. These events introduce the personal element of the "hands on" aspect of God creating. Where Genesis 1 describes God's creative work primarly driven by what He says, Genesis 2 adds His personal touch:
then the Lord God formed the man of dust from the ground and breathed into his nostrils the breath of life, and the man became a living creature. (Genesis 2:7 ESV)
And the rib that the Lord God had taken from the man he made[h] into a woman and brought her to the man. (Genesis 2:22 ESV)
The LORD God is described as physically present. So when He rested on the seventh day, the man and woman rested with Him. By starting Chapter 2 with the the seventh day and then continuing, there is a literary connection with the seventh day to what follows. So the idea of God dwelling with man and woman is implied and reinforced by "attaching" the seventh day to what follows while insuring it was "set apart" from what preceded.