It depends a lot on what cultivar of abelia you are growing. 'Edward Goucher', one of the most popular selections, has a tall, arching habit, looking like fountain over time and in climates where it is able to assume its optimum height. Other forms of xgrandiflora tend to be dwarfer, more mounding plants but IME, any abelia has an ability to produce long leggy shoots that can shoot straight up, even the dwarf forms. If you are not happy with this sort of growth, just prune them off.

Sorry .Its a Rose Creek.

They're all cane-stemmed shrubs that send out arching new shoots that then branch from the sides and fill in later. Except for selections that are a bit too dwarf for the effect to be fully realized this manner of growth eventually results in a graceful, fountain-like appearance that is much of the point of these - with the commonly practiced shearing them into much smaller, tighter shapes completely eliminating this attribute.

Looks like yours needs to be dug up and planted in a spot with more space. Notice the dimensions given here.

http://www.monrovia.com/plant-catalog/plants/837/rose-creek-abelia/

If you look at photos of older examples online this variety apparently becomes quite dense on its own over time.