Should i ask my boyfriends for his myspace and facebook password?

[puppysyndrome]

Use a bit of common sense here sweety! You either trust him or you don't! Just suppose that you can't trust him.........what would be the smart thing for him to do? Perhaps give you the passwords and then create new accounts? If people are doing things they shouldn't, they'll do whatever they have to do to keep it that way and appease their partner!
There's also the other issue........your insecurity and lack of respect for his privacy. EVERYONE is entitled to their own privacy........you AND your boyfriend.
Perhaps you just need to turn the scanner inwards and work on your own insecurities......or if you really and truly feel he can't be trusted, then you shouldn't be with him!