Directly, but gently.
Directly approach the sensitive issue, but don't phrase it in a way that will offend them, because it's a sensitive issue, and so that can go very badly very quickly. A linguist would actually probably be good at this, since there are different ways to phrase things.
Case and point:
I turned down a girl I'm actually very attracted to physically, but I turned her down because there's a significant age and maturity difference between us, and I just don't want to have to deal with that. So, I put it into a perspective that she agreed to ideologically, and that seemed to pacify potential conflict before it started. Thus, working around a problem, rather than through the problem.
Sensitive issues often exist due to irrationalities, and those irrationalities need to be gently approached and lightly unboxed and corrected over a long period of time. Think of it, like tending to a deep wound. Regrettably, usually what happens instead is a merciless direct approach that comes off badly phrased with no acknowledgment to the reasons why that person feels the way that they feel, which gets taken as counterpointed criticism, which brings up conflict and starts a fight because you accidentally offended the person that you're trying to help. So instead of helping them, the result is that you hurt them, which makes the problem/wound even harder/worse.