And if I might add...Genesis 6:1-9
And it came to pass, when men began to multiply on the face of the earth, and daughters were born unto them,
That the sons of God saw the daughters of men that they were fair; and they took them wives of all which they chose.
And the LORD said, My spirit shall not always strive with man, for that he also is flesh: yet his days shall be an hundred and twenty years.
There were giants in the earth in those days; and also after that, when the sons of God came in unto the daughters of men, and they bare children to them, the same became mighty men which were of old, men of renown.
And GOD saw that the wickedness of man was great in the earth, and that every imagination of the thoughts of his heart was only evil continually.
And it repented the LORD that he had made man on the earth, and it grieved him at his heart.
And the LORD said, I will destroy man whom I have created from the face of the earth; both man, and beast, and the creeping thing, and the fowls of the air; for it repenteth me that I have made them.
But Noah found grace in the eyes of the LORD.
These are the generations of Noah: Noah was a just man and perfect in his generations, and Noah walked with God.
The primary issue was that man's "seed" became corrupted. During this time, only Noah and his family remained free from this pollution. This is why it's written that Noah was "perfect in his generations." Noah, and his sons by extension, were still 100% Adamites. When the most High gave man "120 years," it was from the moment of this pronouncement that the flood would come. The primary reason for the flood, though, was to eradicate this new "seed" brought forth from the interbreeding between angels and women. The secondary reason was to put an end to the self-destructive path of man. As it's written, "..the wickedness of man was great in the earth, and that every imagination of the thoughts of his heart was only evil continually."
QUESTION: Was the flood an act of love?
ANSWER: It was toward Noah and his descendants just as much as it is when our own law-enforcement agencies give a criminal a life-sentence, or the death-penalty.
And spared not the old world, but saved Noah the eighth person, a preacher of righteousness, bringing in the flood upon the world of the ungodly.
The most High didn't destroy our ancient world without warning. In the 120 years given before the flood came, Noah preached to the people. This also serves as an act of love on "God's" part.