The phrase "and ever more difficult" is correct and usable in written English.
It can be used to describe a situation or task that is increasingly challenging over time.
Example: "As the project progressed, the requirements became and ever more difficult to meet."
Alternatives: "increasingly difficult" or "progressively harder".
The United States remains mired in a war in which victory seems ill-defined and ever more difficult to achieve.
The growing jihadi presence in Syria makes the question of helping moderate rebels ever more pressing, and ever more difficult, too.
His strength lay in inventing new and ever more difficult maneuvers, bringing him notable success in competition with the European stars of the day despite their stronger, more powerful aircraft.
"The job that we're expecting nursing homes to do is ever more complex and ever more difficult," says Andrea Sutcliffe, chief inspector for regulator the Care Quality Commission CQCCare Quality Commission CQC
Such change is painful because it involves the abandonment of ideals formerly attainable; the vision of a one-size-fits-all medical school becomes no longer practical, and ever more difficult decisions will be needed as to what style(s) of graduate is most urgent for a faculty to produce.
When customers are addicted and willingly infect their friends, strong companies get stronger and become ever more difficult to beat.
The plethora of sports books grows by the year - with the usual handful of rewarding gems and nuggets ever more difficult to come across in the overabundance of the great unread and the great unreadable.
Presidents in the first year of their first term are often at the peak of their popularity, have the biggest margins in Congress, and are free from the scandals and intense partisanship that start to gather around them later and make governing ever more difficult.
Unfortunately, there are worrying counter trends stifling some of these efforts and making it ever more difficult to carry out work with official data.
Without similar high-profile successes in recent years, popular support has fallen, and it becomes ever more difficult to convince incoming foreign secretaries it should be a priority.
While consumers applaud the availability of low fares, complaints about service abound, air travel is less and less convenient, and smaller cities are ever more difficult to reach.
