bad motives or not?

All comes down to trust of your partner.

If you don't have that, you don't have a relationship nor are you ready for one.

It doesn't always lead to cheating or a messy scenario

BUT...it can

Relationships are hard enough as it is...it makes no sense to put yourself in a situation that has a big likelihood of causing problems. Avoidable problems.

If you are their partner, then the only other roles left for others in their lives to play are: Family, FRIEND, co-worker, ex or enemy.

A 'friend' won't come onto you if they see that you're in a relationship.
A 'friend' won't disrespect you by way of disrespecting your partner.
A 'friend' won't wanna bone you or have secret fantasies of wanting to be with you (It's nearly impossible to have unbiased advice or have good motives when you're only entertaining a taken person b/c you like them)

So your man needs to get very clear on how he defines a 'friend.' If she's into him to the point that she's making it known to either of you, then yes she needs to go. Not b/c he will bite the bait one day, but b/c he's not willing to leave opportunity for him to do so one day.

And if this 'friend' was any kind of friend, she'd respect that HER coming onto your man is a huge and justifiable reason for why she needs to keep it moving & go find someone else's man to be quote on quote 'friends' with.

Respect is important. And so if being clear and honest about the real reason you're keeping someone around. Some men don't even intend to bite the bait with these 'female friends.' They just like the ego boost that comes when other women still desire them even though they're already taken...they like knowing that they've still 'got it.' Men have the need to get that validation, attention & ego-stroking, not only when they're single, but also in a relationship.

Them needing it isn't the problem. The problem comes when they're expecting to get that fulfillment from anyone else other than their partner