ofcourse not, cheating is taking the cowardly route. what you need to do is be a man and confront her, tell your woman the lack of sex is leaving you unhappy with your relationship and that if things dont change you will move on to someone who can make you happy.
dont be a scared pantsy who of run around cheating behind her back like a dog with no honor instead of speaking up like man.
shes wrong in what shes doing but cheating is far worse. you have to understand women dont think like men, explain to her how you feel. you wont be able to use your dick properly anyways unless you grow a pair to go with it.