A friend of mine, Tim, is often busy. I've been trying to make plans with him to go out for drinks, but he seems to be busy every time I make this offer. This happens fairly often so I have a slight suspicion that perhaps he's using this as a way of saying "no" in order to avoid spending time with me.
I have no problem not spending time with Tim if he doesn't want to, I'd just rather not spend the effort asking him (which is annoying for me if he'll always say no and annoying for him if he's uninterested) if he doesn't have a genuine interest.
How can I ask him whether or not he has interest in spending time with me without potentially alienating him if he was actually busy every time I asked?
My focus is mostly on asking him in such a way that doesn't imply that I think he's making excuses. He works often and is genuinely busy often so in the case where my timing has been consistently bad I don't want him to think I'm doubting him. I am open to indirect approaches as well.