WASHINGTON—U.S. home sales fell for a fourth straight month in May as record-high prices amid low inventory frustrated potential buyers, a trend that could persist for a while, with builders unable to deliver more houses because of expensive lumber. The decline in sales reported by the National Association of Realtors on Tuesday was concentrated in the single-family housing segment, which benefited from a migration from cities as millions of Americans sought more spacious accommodations for home offices and schooling during the COVID-19 pandemic. Sales are retreating back to their pre-pandemic levels, indicating that the tailwind from the virus is diminishing. “It’s becoming clear that record-high price growth and an enduring shortage of available homes are beginning to hinder would-be homebuyers,” said Matthew Speakman, an economist at Zillow. “Sales volume continues to struggle to regain the momentum it built late last year.” Existing home sales dropped 0.9 percent to a seasonally …