The reason why these two manga are similar is because both deal with a female who is entering a marriage deal with a male because of her money issues/poor issues and tada~ theres the similarity
I like how at the begainning both man what marriage for money but in the end they came to love the woman in the story whole heartly.
If your favorite part of this manga was the controlling guy and the innocent and naive girl, you'll probably find the other series appealing. Ai Ore! has only one controlling guy in it, but Stepping on Roses has two and a love triangle, so the dynamic is a bit different, but on the whole, I think it's a decent match.
Both of these stories start out with the main female character making a deal with the main male character that causes them to leave behind their poverty/common-ness and enter a world of nobility/royalty. Eventually this leads to romances and love triangles that get pretty intense. They have a similar feel, in both story and art, so if you like one, you may enjoy the other.
Captive Hearts and Stepping on Roses focus on two people held together by obligation, a curse in one case and a contract in the other. Things are initially quite difficult for the low-class person, as he/she struggles with the complications of being a part of the mistress/husband's world. In spite of it all, some love manages to blossom anyway.
Haine Otomiya is a student at the elite Imperial Academy. A one-time gang member who was put up for adoption by her father, her life changed when she met Shizumasa Togu, president of the student council and ‘emperor' of Imperial Academy. Haine quits her gang and enrolls at the prestigious private school in the hope of winning Shizumasa's love. When she is hired as his school bodyguard, she's thrilled; but can she survive the drama of the student council? As secrets spill and relationships form, Haine is pulled further into the world of the elite and powerful, where wealth is everything and social status is the basis of all relationships. What's a girl to do?
The female leads in these stories experience a huge change in social status because of their relationships with powerful young men. It's a definite adjustment for each of them: learning how to carry herself, what to say, and how to make her boyfriend/husband look better.