Manhattan Love Story (2002)

Blurb:
In the heart of New York City, florist Dan “Diamond” Loving makes his living selling colorful bouquets to customers looking for a little romance in their lives. Actually, Dan has a romance of his own—a secretive affair with handsome, powerful CEO, Rock Melville. Rock owns a good part of the city, including Dan’s own flower shop, and the business responsibilities which go with that make him a hard man to get to. For some, money and power can be a powerful aphrodisiac, but for Dan, dealing with a workaholic boyfriend has its difficulties. True, the time he does spend with Rock always warms Dan’s heart, but what good is a lover he can only see once in a while? Is Dan destined to always come last in Rock’s busy schedule? Or will Rock make the commitment necessary to keep their love alive?

Source: www.anisearch.com/manga/6475