Perhaps you have more emotional attachment (and therefore more limiting beliefs and blocks) to relationships than you do to objects.
I found at the beginning that manifesting 'things' was a doddle, but bring in something that I felt strongly about and woah - different story alltogether.
For every distinct thing that you try to manifest, you will have a set of beliefs which you need to tweak to align yourself it. Get through this stage of the process and you will get what you want.
Hope this adds some value!