There are times in life where we face things that show us who our real friends are. The ones that care. Third wheels don’t have to feel left out. They can actually be involved quite a bit. If their friends cared about them, they would be happy for them rather than thinking so selfishly. Maybe tell them that they might need to include their third wheel a bit more so they don’t feel so neglected or left out. Other than that, they shouldn’t determine their whole relationship on how their friends feel. It’s how they make EACHOTHER feel that matters.