Have them fixed. They will stay healthier and less costly to maintain and easier to manage. The last thing this world needs is more dogs. The animal rescue places are overloaded now because of irresponsible people. Your dogs love you, love them back.
Please arrange with your vet. To have them both neutered. It is not fair to keep them separate. Would you like a lifetime separate from the opposite sex? Neutered dogs have much less diseases that entire ones. There are too many unwanted animals in the world today through allowing litters to be born. Remember it is a ONE OFF payment for the animals life, never to be repeated. Worked out on a yearly basis. It is cheap. Please be responsible.