I

it like this...
I don't trip off of who my lady is friends with because it always come down to how she feel about me.
If she respect me as well as the relationship, then she isn't going to cross boundaries.
Also, a person can cheat with anyone, anywhere @ anytime, so it goes back to my initial point.
If a woman is finding reasons why she can't spend time with a man, then that should raise concerns. IMO, a woman who is in a relationship should prioritize her time with her significant other. Of course there are other priorities such as work, kids(if applicable), family, rest, chores, friends, etc.
However, her significant other should pretty much take up a good portion of her free time.
Lastly, where I side with OP is if a woman is always talking about her male best friend and she is spending alone time with dude, then that would be a potential deal breaker.
Other than that, I don't trip off of who my lady is friends with, especially considering that women my age are pretty much grounded in their lives and either is into her family, relationship, work and/or all of the above.
Friends pretty much take a back seat to the aforementioned....