The harassment from Alfine ー his girlfriend and childhood friend ー who is the same age, grew up with him, and became adventurers together, is painful. She is a peerless beauty, called the "Flawless Sword Goddess", a person with the title "Sword Master" whose achievements were recognized by the kingdom which made her a knight and a noble title. ...
On the other hand, he is treated as Alfine’s accessory, gets verbally abused by her, and suffers from her harsh harassment, resulting in him losing his dignity as a person. He has resigned himself to spending his daily life in the position of a lover-cum-caretaker.
However, a change came to that daily life. Alfine, who becomes busy as the kingdom's knight, is often unable to take part in adventures. As a result, his solo adventure requests increase, and he is able to regain his lost dignity. Then he becomes aware of the abnormality of his circumstances.
So to regain himself, he chooses to leave her and her repeated harassment behind. In addition to all of the equipment he has received until then, he returns his sword, one of a kind they had exchanged when they became adventurers. Declaring that they are over, he leaves the place quickly.
"From now on, I will change my name and appearance and live freely."
As soon as he decides that, everything goes well. When he realizes, he is praised by the people around him and is the greatest adventurer on the frontier. What's more, he got a proposal to marry the frontier lord’s daughter from a female adventurer.