Love of my life vs. best friend

My boyfriend Russell and I are really really close. But, he and my best friend Seth don't get along. Seth can be a flirt at sometimes, but he's not like that with me. I can actually tell Seth things and he's always been there for me. Russell and I are that close, too, but he and Seth keep yelling at each other and once they almost got into a fight. I don't know what to do. Help?

Explain to them that they are both important in your life and you cannot take their petty fighting and arguing, so they should grow up and set aside their differences and realize what they are doing to you.

I did.. It lasted for about a month and then they started fighting again.

Don't hang out together, make time for both and if either one complains, tell them it is their own fault, they have made the situation what it is.