Ryan worked with the Trump team on the bill and Trump pushed it as hard as he could. It would be handy to absolve him of responsibility on it, but not accurate.
I'm not trying to absolve anyone, but Paul Ryan bears the primary blame, and there's no doubt about that.
However, it can't be reasonably argued that President Trump is trying to sabotage Paul Ryan, but the converse is eminently possible, if not highly probable.
The tax cut issue should be an easy win, absent GOPe sabotage. So Congress needs to get its ass in gear and deliver. They're the governing majority now, and acting like an opposition party is not a legitimate role for them any longer...