When you have had one tourist visa to the UK and your Thai partner has returned on time then the second and third visa application to the UK will be looked upon more favorably as long as you have both kept withing the boundaries of the tourist visa to the UK. You must remember that when you apply the documents you supply have to be complete the same as your first application including photographs of you both in the UK on holiday, do not do as we have seen before where clients have presumed they can do themselves the second time and only produced half the documents required.