Flower Garden (Tohno Kazumi)

From Netcomics:

After a night of drinking, Soko wakes up one morning to find Kaoru, a mysterious young man, sleeping in her bed and unable to remember how he got there. It's bad enough that Soko happens to be engaged to a decent man, Matsuda, but the man she just cheated on him with is only a teenager. Horrified, Soko demands Kaoru leave immediately. Unfortunately, Kaoru is the son of family friends who sent him to the city to live with her for awhile. She has no choice but to let Kaoru stay, if she wants her secret kept. But, her secret isn't the only one around. Matsuda's boss schemes to marry him to an important client's daughter. Kaoru insists he deeply loves Soko. And Kaoru has his own stalkers from the past. Flower Garden is a quirky story about how love is a garden that exists everywhere, the only trick is finding the flower meant for you.