To be fair no one was ever going to be good enough to move in on Pam or replace Bobby.
Alex Ward wasn't popular and Mark Graison wasn't popular with the majority. It was rumoured that Peter Richards might lust after Pam (Shock horror God forbid) but it was poor Sue Ellen who ended up with that story because her reputation warranted it.
Would a nice normal chap wanting Pam have been accepted? Probably not. How about a beautiful hunky rich man? No, because Bobby fitted that bill. A bad guy? No chance!
When Dallas was top dog viewers hated any change. No man was ever going to be good enough to grace Pam's arm.
Mark wasn't a stalker, he was just a guy who really fancied someone. She even used him. Pam wasn't desperately unhappy and didn't need or want saving.
