I never recommend spells. I agree with the other posts as well, if you have already established a relationship with this individual, then you have already opened the door, now its just creating opportunity, which you don't need a spell for, just initiative.
As for some other thoughts, a lot of people use the Ylang-ylang plant to help increase sexual desire. You can buy it in an oil form and wear it, but opportunity to be around that person is key. Since this is no different then wearing perfume it isn't interfering with free will, but rather helping your opportunity come to pass.