I asked an online friend "I haven't see you for a while".
Yeah, life kind of got in the way for a little while.
What doe's it mean? And what's its structure?
It's an idiom that means the routine of day-to-day living (things your friend had to do) had to take priority over things your friend wanted to do.
In this case, it sounds like the demands of day-to-day living (jobs, bills, responsibilities, family, illness and hardships to name a few) had to take priority over socialising with his friends for a while.