no
Yes, there are.
when he has sex with you reallyreallyreallyreallyreallyreallyreallyreallyreallyreallyreallyreallyreallyreallyreallyreallyreallyreallyreallyreallyreallyreallyreallyreallyreallyreallyreallyreallyreallyreallyreallyreallyreallyreally hard
Answer Unless she is dressed as a nun, I do not believe there would be any signs that would indicate whether a woman has ever had a boyfriend or not. And, actually, a nun could have had a boyfriend at some point before so that is really no guarantee either.
If your boyfriend starts to stop showing affection towards you and is always busy and going out instead of being with you. These are signs of your boyfriend cheating on you.
He'll tell you.
If he is your boyfriend, no. He's already committed to you so why play games?
He might be not answer your calls.
http://wiki.answers.com/Q/Can_your_boyfriend_show_signs_of_you_being_pregnant"
not spending time with you and maybe not sleeping with you
punctuality
Does he still smell like it? Does he show any signs of it? Do some research on the effects of marijuana and compare them to your boyfriend.