The phrase 'it becomes difficult' is correct and usable in written English. You can use it whenever you want to describe an event or situation that is increasingly hard to deal with or manage. For example: As the situation becomes more complex, it becomes difficult to know how to proceed.
It becomes difficult.
It becomes difficult to maintain faith.
That's where it becomes difficult".
Because of the resident's reaction, it becomes difficult.
If it becomes difficult, switch to the second tap.
That's when it becomes difficult all of a sudden.
It becomes difficult to decipher what style and dressy is".
"The minute something becomes familiar, it becomes difficult.
There are so many that in practice it becomes difficult.
"Working with someone you don't know, it becomes difficult".
When that is compromised, it becomes difficult to win".
I love the desktop app, it’s always running on my Mac. Ludwig is the best English buddy, it answers my 100 queries per day and stays cool.
Cristina Valenza
Retail Lead Linguist @ Apple Inc.