When a person does not love you (or have the feelings you desire them to have for you), it simply means those energetic particles are not present in their external energy field – because they are not naturally internally present.
What magick does, is it energetically inserts those desired energetic particles into the target's energy field.
In a sense, it works like a virus or radiation. By surrounding the target with the energy of the desired effect, the target's energy field becomes "contaminated" with new thoughts, desires, and in turn: actions.
If and when the "contamination" is persistent and magickally performed properly, the result will be a thorough seep into the physical and emotional mind of the target.
The thoughts and emotions you have planted inside the target's mind will begin to feel as if they are their own.
Once the thoughts and emotions are planted, the target will begin acting upon them.