Medb and her Lovers
Medb was a woman of her time. Under the Brehon Laws of ancient Ireland women had equality with men, they had the power to raise their own armies, hold their own property, participate in the court system as lawyers and judges, as well as pick their own partners. Marriage was a contract not a sacrament and so could last as long, or as short as the couple wished. 20 years or an afternoon.
Medb was not unusual in her number of partners but for what she expected of them;
‘for 'tis I that exacted a singular vow, such as no woman before me had ever required of a man of the men of Erin, namely, a husband without avarice, without jealousy, without fear. For should he be mean, the man with whom I should live, we were ill-matched together, inasmuch as I am great in largess and gift-giving, and it would be a disgrace for my husband if I should be better at spending than he, and for it to be said that I was superior in wealth and treasures to him, while no disgrace would it be were one as great as the other. Were my husband a coward,'twere as unfit for us to be mated, for I by myself and alone break battles and fights and combats, and 'twould be a reproach for my husband should his wife be more full of life than himself, and no reproach our being equally bold. Should he be jealous, the husband with whom I should live, that too would not suit me, for there never was a time that I had one man in the shadow of another.’
From; Pillow Talk, the opening chapter of the Táin bó Cúailnge.
There's a whole Irish text devoted to this called 'Medb's Man-share' (Ferchuitred Medba, which can be seen HERE). The text was also called 'Medb's Husband Allowance', 'Medb's men', or Cath Boinde (the Battle of the Boyne), and you can find the translated version HERE. It comes from a manuscript called the Yellow Book of Lecan, originally.