Bush is about 5 feet high. This is in PNW (Washington state). We haven't been here long enough to see if it flowers or if there's any other specific characteristics that are useful for identification. Happy to go outside again and look again for something specific.
From the information provided it is not easy to specify a name. There are many shrubs which have opposite, toothed leaves on slender arching branches as in your photo. The id becomes much more evident when the flowers are present, and to ensure that you see flowers it is important not to do anything to the shrub until the flowers are produced in the next 12 month period.
For more instant gratification you might consider the Deutzia family of shrubs. There are many of them; if you look up D. gracilis or D. scabra you will find that they sort of resemble your photo - try to find images without the flowers. Focus on the colour of the bark, particularly on more mature wood in the centre of the bush, and the way the bark changes colour from really old wood to the youngest. Also bark often has marks on it like dots or ridges which are the result of growth patterns unique to that species. Another similar species (ignoring the flowers) is Weigela. All will become clear next spring or summer.