How often should my boyfriend stay the night?

Ok so I live on my own and my boyfriend lives 30 miles away we see eachother twice a week and I'm lucky if he stays the night once a month, we have been dating for 10 months now and he lives with his parents till he finds a new job(he is getting unemployment so its not the money) and he always has an excuse for why he can't stay the night and its normally because he doesn't want his parents to watch his dog, they also have 2 dogs of there own so its not like its inconvenient for them, so am I wrong to be upset that he never stays with me?