The childhood friends got married, and they decided to have kids. But they couldn't.. I remember that when I watched it in 2009, for that short 3 minutes at the beginning of the film, I cried for the couple, for not being able to have kids, and subsequently for the man who lost his wife when they grew old. My heart really ached for them.
4 years after that movie, it became personal for me. As I watched the short clip again, I couldn't help but tear again.. I am not sure if we would be like the couple in 'UP' in future..
Infertility issues are not talked about much in society. Pixar and Disney had done a good job including some realistic elements into the cartoon and increasing the awareness of infertility.