godan verb (-u)
swear together; make a joint vow; pledge to each other
Describes two or more people making a mutual promise or oath. Often used in romantic, friendship, or ceremonial contexts.
二人は永遠の愛を誓い合った。
The two swore eternal love to each other.
仲間たちと成功を誓い合う。
We pledge success together with our comrades.