Is it normal someone you like in a relationship breaks up and you feel guilty

I've had a few occurrences now where I've liked someone who was already in a relationship, whether that relationship be strong and already long built, or rather new.

Even though I'm usually a pretty selfless person, I couldn't help but think
"I wish they'd break up so I could have the opportunity to date her."
Or, something to that effect.

Several times now, after this, the person I like has had problems with their relationships, broken up, etc.
After wards, I always feel horrible and deeply regret my thoughts.
"Be careful what you wish for."
And I've never made any advances on them after that, just felt extremely bad and guilty.

Is it normal?