ZDad:
Would you advise someone to trust their daughter alone with her male cousin on a desert island to the extent that you would advise trusting their daughter with her brother on a desert island?
With all due respect, it also doesn’t matter what you think most people think. LiHalacha there is no issur to marry a cousin and there is also no natural aversion as there is by a mother and sister.
Sam2:
I disagree with your contention that it is “clearly not true with a cousin”. It very clearly COULD be true and, by that age, likely is the case that it’s for the wrong reason except in limited circumstances as mentioned by funnybone.