Greetings to all you wonderful Cap people.

I (F) - Sag sun, Libra moon have a crush on this guy (Cap sun, Aries moon). We are both adults (far over 30), in the same professional field, he is currently helping me with something concerning work (via email though, we see each other sometimes by accident). In a month we are supposed to meet, so i can help him with his personal project (it was my initiative to ask/offer). When we meet, he is smiling and everything (we don't talk much), in emails he is very polite and nice - apologizing if it takes him too long to answer and so on. We have met for semi-professional coffee thing once, he asked me a few questions about myself, told me something about himself. Nothing too personal, of course.

My question is - how can I politely and subtle (?) ask him if he is in a relationship, when we meet in a month (not going to do it via email of course, because he also mentioned last time, that is going to be under a lot of work stress in the next weeks, so im going to leave him in peace)? Is it even appropriate to ask? Or maybe there is some indirect way? Will he understand, that i am interested in him, if I ask smth like this? Because, I personally have no problems with people asking me personal questions, but how is it with cap guys? (never dated one in my life).