Like is this used in context of marriage?
kotobank.jp/word/契る-565485– Darius JahandarieApr 1, 2020 at 2:33
契る is a verb meaning 1."to pledge oneself / vow", "to promise/assure/swear that you (will) do something", and 2. "to be in a sexual relationship (as a married/unmarried couple) " and it is in a way an old word. In short, yes you can use it in a context that means a couple getting married, but it would be more proper to say "夫婦の契りを交わす", to vow to become husband and wife or "結婚の契りを交わす".
Other examples "将来を契る" - Pledge the future to each other (to marry each other) "再会を契る" - to promise to see each other in the future