The phrase "often react with" is correct and usable in written English.
You can use it when describing how a person reacts to a particular situation or stimulus. For example, "People often react with fear when they encounter a strange animal."
In contrast, hunters often react with violence and aggression when sabs successfully disrupt a kill.
People with dementia often react with agitation, including pulling out the tubes, and then are either sedated or restrained.
East Coast visitors often react with wonder-cum-horror at the neighborhood, while even in Hollywood's monied upper echelons, some consider Beverly Park to be too much.
The Ahn Cheol-soo phenomenon speaks volumes about why many Koreans often react with distrust to initiatives trumpeted by the political and corporate elite, like the contentious free-trade agreement with the United States, and why Mr. Lee, while winning the admiration of President Obama, is often regarded by his own people as out of touch.
They note that voters often react with the automatic lizard response to political choices.
When the house fills up again, parents often react with mixed emotions.
When my fifth grader sees me in school, she often reacts with irritation.
Despite her involvement in the fashion world, she is the self-professed "tomboy" of the family and has often reacted with discomfiture to her sisters' performance of flamboyant femininity.
David Goodwillie, so often a decisive player in the final third, often reacted with doubt when the final pass opened up and his display was undermined by poor decision making at key moments.
Faced with Aboriginal resistance settlers often reacted with violence, resulting in a number of indiscriminate massacres.
Patched areas often react differently with stains than the rest of the concrete, resulting in a strange discolored area.
