Thayer's on "agape" love -
ἀγάπη, -ης, ἡ, a purely Biblical and ecclesiastical word (for Wyttenbach, following Reiske's conjecture, long ago restored ἀγαπήσων in place of ἀγάπης, ὧν in Plutarch, sympos. quaestt. 7, 6, 3 (vol. viii., p. 835, Reiske edition)). Secular authors from (Aristotle), Plutarch on used ἀγάπησις. "The Septuagint use ἀγάπη for אַהֲבָה, Son 2:4-5; Son 2:7; Son 3:5; Son 3:10; Son 5:8; Son 7:6; Son 8:4; Son 8:6-7; ("It is noticeable that the word first makes its appearance as a current term in the Song of Solomon; -- certainly no undesigned evidence respecting the idea which the Alexandrian LXX translators had of the love in this Song" (Zezschwitz, Profangraec. u. Biblical Sprachgeist, p. 63)); Jer 2:2; Ecc 9:1; Ecc 9:6; (2Sa 13:15). It occurs besides in Sap. 3:9; 6:19. In Philo and Josephus, I do not remember to have met with it. Nor is it found in the N. T. in Acts, Mark, or James; it occurs only once in Matthew and Luke, twice in Hebrews and Revelation, but frequently in the writings of Paul, John, Peter, Jude" (Bretschn. Lex. under the word); (Philo, deus immut. sec. 14).
From Abbott-Smith's Manual Greek Lexicon of the New Testament on "agape" love -
ἀγάπη, -ης, ἡ, love, goodwill, esteem. Outside of bibl. and eccl. books, there is no clear instance (with Deiss., LAE, 184, 705, cf. the same writer in Constr. Quar., ii, 4; and with MM, VGT, s.v., cf. Dr. Moulton in Exp. Times, 26, 3, 139).
SYN.: φιλία G5373 *. ἀ., signifying properly (see ἀγαπάω G25 *) love which chooses its object, is taken over from LXX, where its connotation is more general, into NT, and there used exclusively to express that spiritual bond of love between God and man and between man and man, in Christ, which is characteristic of Christianity. It is thus distinct from φιλία, friendship (Jas 4:4 only), στοργή G? , natural affection (in NT only in compounds, see ἄστοργος G794 *) and ἔρως G? , sexual love, which is not used in NT, its place being taken by ἐπιθυμία G1939 *. (Cf. ἀγαπάω; and v. Abbott, Essays, 70 f.; DB, vol. i., 555; Cremer, 13, 593; MM, VGT, s.v.)
About agape love, Thayer's reads ", a purely Biblical and ecclesiastical word" and the AMGL says "Outside of bibl. and eccl. books, there is no clear instance".
In addition, notice in the AMGL paragraph of synonyms, the following line -
"...and ἔρως G? , sexual love, which is not used in NT, its place being taken by ἐπιθυμία G1939" This is the sexual love "eros" that is not found anywhere in the NT or LXX.
The LXX translators appear to have sanitized the OT of the idea of sexual love. The LXX uses "agape" love for the rape of Tamar by Amnon -
"Then Amnon was seized with a very great loathing for her; indeed, his loathing was even greater than the lust(H160, ’’ahăbâh) he had felt for her. Amnon said to her, 'Get out!'” (2Sam 13:15 NRSV)
Where the NRSV has "lust" for ’ahăbâh, the LXX translated this sexual lust as agape love. What were the LXX translators thinking?
I recommend reading a scholarly online article that starts with the following sentence: "This short article intends to explain why all love is God’s love. It begins by showing how the translation of the Hebrew Bible into Greek, in approximately 200 B.C.E. distorted a Jewish and Christian understanding of love to exclude erotic love from God’s purposes."
medium.com
ἀγάπη, -ης, ἡ, a purely Biblical and ecclesiastical word (for Wyttenbach, following Reiske's conjecture, long ago restored ἀγαπήσων in place of ἀγάπης, ὧν in Plutarch, sympos. quaestt. 7, 6, 3 (vol. viii., p. 835, Reiske edition)). Secular authors from (Aristotle), Plutarch on used ἀγάπησις. "The Septuagint use ἀγάπη for אַהֲבָה, Son 2:4-5; Son 2:7; Son 3:5; Son 3:10; Son 5:8; Son 7:6; Son 8:4; Son 8:6-7; ("It is noticeable that the word first makes its appearance as a current term in the Song of Solomon; -- certainly no undesigned evidence respecting the idea which the Alexandrian LXX translators had of the love in this Song" (Zezschwitz, Profangraec. u. Biblical Sprachgeist, p. 63)); Jer 2:2; Ecc 9:1; Ecc 9:6; (2Sa 13:15). It occurs besides in Sap. 3:9; 6:19. In Philo and Josephus, I do not remember to have met with it. Nor is it found in the N. T. in Acts, Mark, or James; it occurs only once in Matthew and Luke, twice in Hebrews and Revelation, but frequently in the writings of Paul, John, Peter, Jude" (Bretschn. Lex. under the word); (Philo, deus immut. sec. 14).
From Abbott-Smith's Manual Greek Lexicon of the New Testament on "agape" love -
ἀγάπη, -ης, ἡ, love, goodwill, esteem. Outside of bibl. and eccl. books, there is no clear instance (with Deiss., LAE, 184, 705, cf. the same writer in Constr. Quar., ii, 4; and with MM, VGT, s.v., cf. Dr. Moulton in Exp. Times, 26, 3, 139).
SYN.: φιλία G5373 *. ἀ., signifying properly (see ἀγαπάω G25 *) love which chooses its object, is taken over from LXX, where its connotation is more general, into NT, and there used exclusively to express that spiritual bond of love between God and man and between man and man, in Christ, which is characteristic of Christianity. It is thus distinct from φιλία, friendship (Jas 4:4 only), στοργή G? , natural affection (in NT only in compounds, see ἄστοργος G794 *) and ἔρως G? , sexual love, which is not used in NT, its place being taken by ἐπιθυμία G1939 *. (Cf. ἀγαπάω; and v. Abbott, Essays, 70 f.; DB, vol. i., 555; Cremer, 13, 593; MM, VGT, s.v.)
About agape love, Thayer's reads ", a purely Biblical and ecclesiastical word" and the AMGL says "Outside of bibl. and eccl. books, there is no clear instance".
In addition, notice in the AMGL paragraph of synonyms, the following line -
"...and ἔρως G? , sexual love, which is not used in NT, its place being taken by ἐπιθυμία G1939" This is the sexual love "eros" that is not found anywhere in the NT or LXX.
The LXX translators appear to have sanitized the OT of the idea of sexual love. The LXX uses "agape" love for the rape of Tamar by Amnon -
"Then Amnon was seized with a very great loathing for her; indeed, his loathing was even greater than the lust(H160, ’’ahăbâh) he had felt for her. Amnon said to her, 'Get out!'” (2Sam 13:15 NRSV)
Where the NRSV has "lust" for ’ahăbâh, the LXX translated this sexual lust as agape love. What were the LXX translators thinking?
I recommend reading a scholarly online article that starts with the following sentence: "This short article intends to explain why all love is God’s love. It begins by showing how the translation of the Hebrew Bible into Greek, in approximately 200 B.C.E. distorted a Jewish and Christian understanding of love to exclude erotic love from God’s purposes."
All Love is God’s love — sexual desire, romantic love, and attachment
This short article intends to explain why all love is God’s love. It begins by showing how the translation of the Hebrew Bible into Greek…
. Hard to say that with a straight face 
