In the Ritacchi-ka no Musukotachi (The Rinucci Brothers) series:

Vol. 1 - Yuuyami ni Kichizuke (Wife and Mother Forever)
Evie Wharton is a free spirit -- the complete opposite of millionaire and single dad Justin Dane -- but she wants to help his troubled son. Evie soon discovers, however, that behind Justin's dark and brooding demeanor hides a painful past. And, against her better judgment, she begins to fall for him....
Can Evie be the one woman to help Justin face his demons? Can she help him find the family he never knew and, most importantly, show him how to love and trust again?

Vol. 2 - Jounetsu no Yokan (Her Italian Boss's Agenda)
LOVE ISN'T ON HER AGENDA
Olympia Lincoln is so relieved when her new assistant shows up, she sets him to work immediately. What she doesn't realize is that he is none other than Primo Rinucci, her new Italian boss!
BUT HE HAS OTHER IDEAS!
Primo can't resist playing along with the harmless deception. After all, this way he can get really close to the beautiful and attractive Olympia. But Olympia has been betrayed before, so when she discovers the truth will she ever be able to trust him again?
(from fictiondb)

Vol.3 - Rome no Hirouen (The Wedding Arrangement)

Vol.4 - Owaranai Koi (The Italian's Wife by Sunset)

Vol.5 - Utsukushii Maboroshi (The Mediterranean Rebel's Bride)

Vol.6 - * Aiyue no Meikyuu * (The Millionaire Tycoon's English Rose)

English version via Renta!:
Vol 1, Vol 2, Vol 3, Vol 4, Vol 5, Vol 6