Fletcher Cox says his relationship with a married woman ain't the result of some master seduction ... but just some good ol' fashioned mutual attraction between consenting adults.
TMZ Sports broke the story ... Cox -- Eagles star DT -- was sued by Josh Jeffords, a North Carolina man who claimed Fletcher seduced and banged his wife Catherine ... destroying his marriage.
In N.C., that can constitute "alienation of affection" ... what Cox is being sued for.
But in docs filed by Cox's attorney, he's adamant he's no homewrecker ... saying the relationship "was not the result of seduction," but just "mutual attraction" with a woman who "knowingly and voluntarily consented to the relationship."
In fact, Cox says she never told him she was married ... and says it wouldn't matter anyway, 'cause "no genuine love or affection existed" between Catherine and her husband.
The 6'4," 310-pound Pro Bowler does admit to having explicit text conversations with the woman ... including telling her, "I want to get you pregnant."
Cox's attorney is asking the court to dismiss the case ... and make Josh Jeffords pay for his lawyers.