My boyfriend has me upset!

Samantha • I`m an English girl in love with my handsome boyfriend!
I love him to bits but come to find out, he's been lying about a friend. He told me at first that it was a guy friend he was going to hang out with, but my girlfriend Sammy saw him at Asda with some blonde chick when he said he was over at Dave's flat playing games. Is this a red flag? I haven't confronted him yet because to be quite honest I'm afraid of what he will say.