This scene may kill you inside for a moment. But then you have to realize that it shows how strong Chandler and Monica relationships are.
Monica wanted to have a baby since the very first season more than anybody else and when it appears that she and Chandler have problems and there is a big chance for them not have a baby in natural way at all, they don’t run from it. What they do is comforting each other, they stay strong and decide to deal with this problem by any way possible instead of running away from it. They don’t let problems influence their love, they struggle against obstacles. That is why this scene is so strong actually.