Patriotism is a love for your country, not necessarily for its leaders. As Mags says, if you believe your leaders are actually betraying your country's values, doing what's in the worst interests of your nation, the patriotic thing to do is question it.
Patriotism relates to being proud to be from the nation you're from. I'm proud to be English, I was proud when we won the Ashes and sent the convicts packing, I am proud of my little quirks and odd phrases that Americans seem to love...am I proud of every aspect of my country's history? No. Colonialism is just one example. Now I am aware of the benefits of colonialism, and I believe overall a positive impact has been felt on some countries (like India) but the policy was still flawed and some practices were just downright barbaric.
I love England, I love everything it stands for, but I don't always love the way the politicians handle things. That's patriotism if you ask me.