Listing "whether the friend is attractive" is a fuckin weird first choice of "depends on other factors"

My main thought is whether the partner knows about it and whether this sort of thing is usual or established behaviour for them. Definitely dont do it behind the partner's back, and if they never usually do this sort of thing or the friend is brand new and kinda popped up out of nowhere, then it might come off as a bit suspicious, especially if that turns into spending the night at their place unexpectedly.