Onna Hakushaku Amber ni wa Shousai ga Aru!: Yatto Jiyuu ni Nareta node, Saikon Nante Okotowari

Amber, the only daughter of an Earl, was married to Brandon of a Marquis family in an arranged marriage. Amber went along with the condition of the marriage that Brandon would manage the Earl's assets, but he had no talent for the job, squandered the fortune, and even eloped with a maid. However, Amber secretly worked a side job behind her ex-husband's back, and used that experience to start a series of businesses, including a clothing store, a beauty salon, and a bar. Just when she was delighted that each business was on track, a certain truth came to light and she found herself in a difficult position. Then, a beautiful young man, the mysterious painter Christian, appeared and made a surprising proposal...!?

(Source: Kadokawa, translated)