life isn't all rainbows and unicorns
Real life does not just consist of innocent, carefree happiness; there is more hardship or suffering in reality than one realizes. I know it's ugly having to see someone you cared about betray you like that, but life isn't all rainbows and unicorns. Friends who aren't parents themselves will have a harder time realizing that life isn't all rainbows and unicorns when you have a new baby in the house.