What is a "Ru'ach Kin'ah"?
Rashi: It is a spirit of jealousy that prompts him to take action.
What does "Vekinei Es Ishto" mean?
Rashi: It means that he warned his wife not to seclude herself with the man whom he suspects of having an affair with her. 1
A precondition to becoming a Sotah.
What are the implications of "Vekinei Es Ishto ve'Hi Nitma'ah ... ve'Kinei Es Ishto ve'Hi Lo Nitma'ah"?
Rashi and Rashbam: It implies that he warned his wife not to seclude herself with the man, and she did, but he does not know whether they were intimate or not.
Seforno: It means that he warned her either because he was imbued with a spirit of jealousy, when he realized that she had departed from the path of Tz'niyus, or for no apparent reason, and either way, she contravened his warning.
What are the connotations of "Ve nisterah ve Hi Nitma'ah"?
Rashi #1: It means that she secluded herself with the man long enough to have been intimate with him.
Rashi #2 (in Yevamos, 58a): It means that since she secluded herself with the man, she becomes forbidden to her husband as if she commited arultery