There could be some communication issues between you. When your buddy tries to talk about fun, lighthearted subjects, you'll steer the conversation toward darker, more serious matters. They'll find you to be quite intense in both your emails and your face-to-face conversations.
You'll often try to dominate the discussion and you won't allow them to simply skim the surface of anything. Digging deeply will be much more stimulating and important to you than it is to your friend; you just won't be interested in anything less, and you'll push them to be explicitly honest in their self-expression. This could be a growth experience for them, but one that's not always very fun or pleasant. And you could end up wearing them out by making everything so intense all the time. After all, sometimes your buddy just wants to laugh and have fun with you, instead of uncovering and analyzing yet another inner wound! Allow them to think and express their ideas in the way that comes naturally to them.