People often plant these near the house so that they can enjoy the sight of the butterflies without having to go into the garden - for this year could you thin out some of the branches so that you can 'see through' it and still get (and give) the benefit of the butterflies and bees - and then take some cuttings - then when your cuttings are big enough to replace the current bush you can plant them further away from the house, and remove the original without detrimentally affecting the food supply for your beneficial garden insects.
And don't forget that each spring you can prune the buddliea right down to below knee height, even if it's a mature bush - so the fresh growth each year shouldn't get too big.
