If there’s one thing I’ve noticed, it’s that expectations are typically the root of the demise of most things. Think of happiness for instance. One day you’re on top of the moon, everything is wonderful, and you’re exuberant. You love it, but you forget to be practical, so without thinking, you inadvertently expect you’ll wake up the next day the same way you did today: instantaneously happy. Morning comes, and you coincidentally are awoken in the middle of a sleep cycle. This sudden unpleasantry is due to your adorable dog fluffy, pawing at your sides, begging to be let outside. Yesterday, fluffy’s pawing and soft whimpering was endearing, but today it unnerves you. Your day is off to a terrible start, and you suddenly resent everything around you and realize that yesterday’s good mood was far too fleeting. It’s not necessarily fluffy, or even the things you begin to resent. Rather, it’s the expectations you’ve put on everything. You have to consciously enable yourself to be receptive and seeking of good vibes, but not expectant of them. The good vibes and energy are free flowing and not intended to be grasped by a death grip. Everything in life should be viewed as sand, rather than that jello sack toy that was popular in the ’90’s (just looked up the official name…they’re called pearl water wigglies apparently XP). Although for those of you who ever got your hands on those things, you know you have to balance them and actually not grasp hard, or they too will slip right from your hands. 
So maybe view the good vibes and feelings as the Pearl Water Wigglie. Balance it and let it flow between your hands, don’t squeeze it. 
I will admit, I too have fallen prey to my expectations. I’ve experienced a yoga high once… I only say once because I know without a doubt, that I’ve only achieved that euphoria once. I believe the reason I haven’t achieved it since is due to my expectations of savasana (a yoga nap/ guided meditation). I got my yoga high when my teacher lead the class through a guided mediation one night. She hasn’t done the guided meditation since, and as a result, I’m left alone with my own thoughts as we all lay in silence. I don’t know if any of you have been able to notice yet, but I have a billion thoughts running through my mid quite frequently. Well during savasana, one additional thought is the expectation of achieving the yoga high/ hoping my teacher will do the guided meditation once more. If you were wondering, neither has happened for quite some time…
But alas, I will be letting go of my expectations, and hopefully manage to clear my mind so that I may once again achieve the blissful yoga high. 
Back to expectations though. Expectations also seem to ruin relationships. Whether they be sexual or platonic, it can create an unbalance. Say your friend and you happen to bump into each other at your favorite coffee shop, and each time you run into one another, you take a few minutes to sit down and have a chat. Then one day, your friend doesn’t show up like usual. You never plan to run into one another, but you assumed they’d be here. You cleared some time specifically for this, and had a topic you were particularly excited to discuss with them. So you end up sitting alone sipping your coffee and watching the interactions around you, and leave without having muttered a word to a single soul. You call your friend and angrily ask why they didn’t show up. They explain something came up at work and they had to skip their regular coffee break. After hearing the excuse you become reasonable, but still hold resentment towards them. It’s these small invisible unwritten contracts that one party conjures up one day that creates a rift in things when you unexpectedly don’t comply to the invisible clause on page 4 index 5 of their contract of expectations.
It’s your friend not showing up to an unplanned coffee, not your wife of 15 years cheating on you… So to an extent, I think one could see those expectations are a little unreasonable. 
Now let’s talk about expectations in a romantic relationship. There are many many many expectations in this case. Sexual favors, romantic gestures, gifts, and all of the expectations of a best friendship have the possibility of being put on this dynamic. 
I’ll just make it short and break it down for this particular set of expectations. It’s typically the result of wanting your partner to read your mind. Such as a thought like this “I shouldn’t have to tell them this, he or she should just know that chocolate makes me upset on April 22nd.” Ok maybe if you told your spouse, partner, or boyfriend/ girlfriend that strange of a fact, they would remember, but if you never told them, how in the world would they ever know? It’s nearly that difficult to read someone and figure out what it is that would make them happy when they’re just in a silent slump. Or possibly your partner is asking something of you that they know you can’t provide them, and therefore, you can’t ever meet those expectations. 
Maybe there is someone who can read your mind, but perhaps there also exists just as an amazing of a person who needs a little nudge in the right direction. 
Though I won’t knock the idea of expectations all together, I suggest an alternative. You can have standards instead. If someone isn’t able to satisfy your projected needs, then you can separate, rather than sit silently waiting for them to suddenly transform into a mind reader.  
If in the scenario of the coffee with the friend, you two actually agreed to meet for coffee, and they continually flaked and never called to notify you, you can just minimize the let down by reducing how often you plan a coffee meet up, or be ok with being alone every so often when they don’t show up.
I’d say standards and expectations only differ in one aspect. Actually scratch that, maybe they’re synonymous and it simply depends on the person who possess the expectations. Maybe it all boils down to insecurity and security with oneself. Or the possession of fulfillment within yourself, that curves the let down of unmet expectations. 
Sorry to not meet your expectations with a finite resolution to this topic, but maybe this is the way it was supposed to end. To serve as a lesson to us all, let go of your expectations and just enjoy the read (or ride).