So you guys net 7200 a month, bills are 1600 a month. I would personally do it income based so maybe 600/1000 bc i like even numbers but you guys arent living paycheck to paycheck. Either one of you could comfortably afford the whole thing so just choose whatever you are comfortable with. But seriously if this is causing a hiccup you should be on relationship advice. It would be different if the expenses were taking up somebodys entire paycheck but yall are doing just fine.