Peter Grill to Kenja no Jikan
The story centers on the titular protagonist, the adventurer Peter Grill, the "strongest man in the world." While he has a girlfriend named Luvilia who he sworn to spend the rest of his life with, Luvilia still believes that babies are delivered by storks, and in the two years since their relationship began, Peter and Luvilia has not progressed beyond holding hands.
In the meantime, various other women, such as two ogre twins and an elf, all want him so that they can bear strong children. Peter has to avoid all manner of temptation and plots, all while feeling guilty toward Luvilia.
(Source: Anime News Network)