i need advice on if shes showing the signs of cheating

so my wife and i are military. im prior service and shes still active. i work a full time job now and shes on the ship till christmas and then goes back out for a few months. our marraige started off amazing like the thing you read in a book and then it just changed. sex isnt intamate anymore and i feel like we cant talk. when i try to sit with her it turns into an argument. even about the simplest things. i think she may have cheated or is cheating because shes accused me of cheating several time out of nowhere, skips foreplay all together and would rather have a five minute quickie. shes even said just get it over with. i always have to ask if shes in the mood and she never asks me. now i understand the late hours thing but when her duty hours shift whole days to when she wont see me at all or she works till 10 at night and isnt hungry i start to wonder. shes even cleared my bank account and says its for bills and i cant see hers at all. now the thing that scares me is while she on the ship the only communication we have is email and ive been told by several friends what happens on the ship stays on the ship. with email she could lie and bullshit without even bliking because its not to my face. what do i do