Constantly engrossed in something

If I'm engrossed in something, I won't think, I won't remember, And time will pass. But... It comes back. Things you originally recommended to me, Things you taught me, Things we did together. We talked so much. I get engrossed, Forget everything, And then suddenly, When I take a break, The moments I remember. Why am I doing this? Why am I doing this alone? No matter how well I do, No matter how much fun happens,