is irrationality always bad ? i need help !

[AtheistPhil]

I am starting to doubt that rationality is the only way to think, i mean outside religion there are phenomenon that we believe in although there is direct evidence contradicting it. An example is love. It has been proven to be a chemical reaction created by hormones, is it the best thing to believe that ? If we all believe that everything we do is only due to chemicals running around our brain, and that life is not really more than anatomy... It is a bit sad is it not ? In that way i can understand people believing in a soul, a purpose, or even a sky daddy.

It may be sad but if it's the truth you'd better have a heck of a good reason to prefer anything else to it.
As Carl Sagan said: "It is far better to grasp the universe as it really is than to persist in delusion, however satisfying and reassuring".
I think fearing that the world might be really cold and inhospitable is natural, as well as considering irrational beliefs to make oneself feel better. But if you do embrace those beliefs, you should know that whatever you do, reality will come back at you the hard way sooner or later. The best way to my knowledge to deal with reality is to face it,. Just like any problem: ignoring it wont get it solved.

Is blissful ignorance always wrong ?

In most cases. The only exception would be when knowledge of reality opens some sort of Pandora's box.