what happened to commitment?

it's sad that relationships don't last in general. I found out that my cousin's 'soon-to-be' ex-husband is divorcing her while she's seven months pregnant with their second child. It really makes me sick how a seemingly healthy relationship can not last. I guess commitment has a shelf-life expectancy. Luckily, there are some loyal people out there and my boyfriend is one of them. He said to me when we were became serious about our feelings and our goals that he's a 'one-woman' kind of man and would never betray my trust. Out of my parents' siblings, my own parents' relationship has lasted the longest and luckily, they are still together. I don't expect my life to be perfect, just to be comfortable and I'm sure my happiness will be enough to make it last.