you said it could be potentially embarassing for them... so why don't you respect the fact that they weren't ready to share that part of their life with you quite yet?
just because you're open and honest with them about everything doesn't mean they have to be, too... and if they aren't then that doesn't automatically mean they shouldn't be trusted. sometimes people simply need more time to warm up to others and find ways to express themselves. don't try to change them, instead try and understand them... by listening to what they DO tell you. the more you listen and the better you listen, the more they'll tell you. i promise.
