The US and western nations have just one country in the region thats not going to attack their embassies and thats Israel. Besides a few alternate reality people, we realize that Israel is surrounded by nations not friendly or at best ambivalent about western democracies. For example Israel is the only safe place for gays.
That explains the reasoning behind viewing Israel as a solid ally, which is definitely is, but it does NOT explain the incredibly intense way some people view the relationship.
Israel may be our closest ally in the region, but the bar is set ridiculously low by the rest of the countries there. It's hard to compare them super favorably when taken on a global scale and compared to countries like the UK, for instance. Yet among all our allies, Israel enjoys, by far, the strongest support in the US for backing any Israeli interests, policies or actions. The suggestion that the US may have divergent interests, even a little bit, earns pretty significant political backlash in the US.
Which isn't to say that Israel isn't a valuable ally in the region that we should certainly support, especially considering their neighbors. But I doubt I'm alone in thinking that the way our friendship is portrayed goes a bit too far sometimes.