What is the so-called "Boyfriend Loophole” in American gun laws?

The so-called “Boyfriend Loophole”, present in the gun laws of many states, refers to a gap in existing legislation that prevents someone accused of domestic violence or stalking from purchasing a firearm.

Under many current statutes, only married offenders are included in the prohibition; dating partners, co-habiting partners, and family members are excluded. New research shows that 82% of domestic violence occurs between dating partners, with the rest attributed to married or previously married abusers (University of Pennsylvania, Journal of Preventive Medicine, 2017).

Additionally, a victim of domestic violence is 5x more likely to be killed if a firearm is present. Revising this language is essential to saving lives, which is why Oregon Governor Kate Brown is backing House Bill 4145, which aims to close the gap.  What is your state doing to protect victims and the public?