To answer your questions - since I've moved out of town, he's only stayed here for an overnight once & only visited twice. I am the one who does the visiting.
Sleepovers are usually on weekends, but have extended over some weekdays. (Weekdays are harder because I work 45 mins away from his place) And I'm there pretty much every weekend, probably 7 out of 8 the last few months.
There have been times where he feels it's too much and limits my visit to one night but there have been other times when he asks for me to stay longer. I just go with the flow! I can't say I've felt that it's ever been too much for me.
I'm sure I could leave more stuff there, but I've been kinda waiting on him offering me a key before I start leaving too much stuff there...(He has a key to my place)
He knows I'll come back - I'm the one who worries that I won't be asked back.
On another note, we started a more serious conversation last night...H is researching codependent relationships. Sounds like that is one of his fears...I can see why he worries about that - he had a horrible experience with my leaving, along the lines of life was not worth living. He says he would never go to that place again, but it must still be worrying him a little.