Tell Him The Truth, Or Spare His Feelings?

Okay, so it's been awhile since I've asked for you guy's help, but here I am again, more for an opinion this time tho...

Is it more important to tell someone the truth, or to not tell them for fear of crushing them? Please don't say that it depends on the situation, but if you really think it does let me know and I'll try explain.

Basically...I just want to do the right thing, even though he definitely doesn't deserve it...I just want to be a good person, but I don't know what the right thing to do is, or if there even is one...But any advice or opinions would be so greatly appreciated!

Thanks to whoever reads this...