It's pretty easy to feel alone.
“Let your conduct be without covetousness; be content with such things as you have. For He Himself has said, ‘I will never leave you nor forsake you.’ So we may boldly say: ‘The Lord is my helper; I will not fear. What can man do to me?’” ~ Hebrews 13:5-6
I'm not even going to say how easy it is to feel forsaken, forgotten, left out.
I think you have a pretty good idea already.
And when you feel alone, it's easy to start doubting God's goodness, to start wanting the blessings He's given someone else. To start wanting the life, the mission He's given someone else.
It's the old "The grass is greener..." phenomena. We don't like our classes, so we start envying our friends who are already graduated and working. We don't like our jobs, so we envy those "kids" who are still living it up in high school and college. Or we start wondering why we didn't get so-and-so's career, or we wonder why God is using Person Y over in Ireland while we're stuck here waiting tables and applying to jobs, hoping we'll get something soon which allows us to have more than ramen on the weekends.
Although at first the pieces of Hebrews 13:5-6 don't seem to quite fit together, if you take another look, you start to see how God put the pieces together.
It's when we're discontent that God feels distant.
It's when we're caught up in lusting after others' belongings/experiences/lives that we feel God must have left us.
Because if He really loved us, why wouldn't He give us what we want so badly?
Why would He make Lady Z's life so much more spetacular?
And we begin to doubt that He cares.
We begin to doubt that He can provide after all, that He actually is looking out for us.
We begin to believe the devil's lie. We begin to think God's deserted us.
Comparing ourselves to others is a dangerous trap.
When we compare, we never feel good about ourselves for long.
But when we stop, when we realize how much God has done for us, and that, no matter what situation we're in, He's watching over us, those feelings of abandonment disperse.
Because we realize the truth.
God will never leave us or forsake us.
He will work it all out.
He will make our lives into what best serves His purpose.
And of course that's going to look different from Person Y. Chances are we have different purposes.*
Kind of silly to think God's abandoned us because our lives are different, don't you think?
*Of course, every Christian has the same core purpose to serve and glorify God (this technically is every bit of creation's purpose). But how it will be manifested in our lives will differ. Some will glorify God through the sciences, others by staying at home and raising godly children, etc.