Queen’s Harem

At the end of a long war, Leticia Veletium, the sole heir to the victorious kingdom of Lakia, declares at her coronation:
“For the peace of the kingdom, I vow never to marry for the rest of my life. However, I plan to establish a harem of consorts to produce a rightful heir to continue the royal lineage.”
After careful selection, three men were chosen:
Kael Romus, from Lakia’s most influential noble family and a childhood friend of Queen Leticia.
Harkan, the knight who supported her on the battlefield.
Elody Rias, a descendant of the old royal family of Jamel, offered to her as a symbol of surrender.
These three became Leticia’s consorts.
Leticia couldn’t understand.
“Your Majesty, it’s fine. The wetter it is here, the smoother the insertion will be.”
“I-Is that so?”
“So, let me make you even wetter. You need to plant your seed.”
Even the one destined to become the kingdom’s chancellor.
“No, my queen. Call me disloyal, tear out my hair—I don’t care. But if you try to cast me away from your side, that’s the one thing I can never forgive.”
Even the war hero with a guaranteed title and future.
“Your Majesty, you need to conceive.”
Even the prisoner from Jamel she intended to teach and send back.
None of them seem to have any intention of leaving her harem… why is that?