Aggression in a 2 dog house

Hello everyone. So I have 2 dogs only about 1 year apart in age. My female is the oldest at almost 2 and my male at almost 1. When my youngest came in as a 4 month old puppy, my female was very loving and cared for him and play spared gently with him. He got older and bigger and of course as expected she became more aggressive to show her disinterest. Just growls and snips. I can't remember the very first fight well or what started it but it has gotten more common and aggressive lately. If I see body language or a circumstance that indicates they may fight, it is easy to distract them or deescalate the situation before they fight. If they lock on though, it is very difficult to separate them, but it can be done with out any misdirected aggression toward me. Today they fought with no prior tell it was about to happen. Im sure there were subtle signs I missed but it was calm in the house. Im so tired of the fighting and the constant having to look over my shoulder every time I move to make sure the environment is zen enough not to worry about a random brawl. Suggestions are greatly appreciated!