My brother's wife and I have a fight

This is not the first time my wife has gotten mad at my brother's wife but this time she is really mad.<br><br>My brother and his wife have been trying for a baby for years, they are now expecting.<br><br>My wife and I have been trying for a year now but no luck.<br><br>My wife got pregnant the first time in February and miscarried. Since then she has been unable to get pregnant.<br><br>My wife has been seeing a specialist and getting all the tests run and nothing seems to be the problem.<br><br>She was upset that my brother's wife got pregnant so easy but she is happy for them.<br><br>This is not the first time they have fought but this time it is really bad.<br><br>She is so upset that she can't even eat.<br><br>I've tried talking to her and comforting her but it's not working.<br><br>I don't know what to do.