Fetching details from the dictionary...

don't get me wrong, but ...; I'm sorry
在庫切れのためご要望に添えませんが悪しからずご了承願う。
We cannot fulfill your request due to being out of stock; please understand.
ご期待に添えない場合は悪しからずご了承ください。
If we cannot meet your expectations, please accept our apologies.
在庫切れの際は悪しからずご容赦願います。
We ask for your understanding if the item is out of stock.