Is it normal for people in serious relationships to develop crushes on others?

My friend has been with his girlfriend for 5 years and has even considered marrying her. However, I know he's developed some pretty intense crushes on other girls during those 5 years. He never acted on them but he did have a lot of feelings for them. Is this normal when you're in a relationship?Is it normal for people in serious relationships to develop crushes on others?
yes that's why some people get a divorceIs it normal for people in serious relationships to develop crushes on others?
of course it is. attractions happen but as long as he remains faithful then he's being a very good man. i have crushes my bf does too, he's 31, i'm 21. we trust each other completely so i have no problems with it and neither does he, we will never act upon it.
yea its normal, in a serious realationship one always does somthing to question it. plus hes young its hard rejecting other girls, but if he truely cares about her he wont do anything to mess it up.
it's human nature. there is a reason he is staying faithful...he loves her. if he strays, thats another story.
yea i been in a relationship for 2 years and i had some crushes on other girls but u get over them
i guess...yea...aslong as he never acted on them...

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