I have a casual question. I've been working at a new job for about a month, and since I'm very shy I haven't made more than a few casual acquaintances who I occasionally exchange words with during the day. Since I work in a restaurant kitchen where everyone's always chatting, I probably seem awkwardly quiet (I have social anxiety disorder and am naturally introverted anyway - plus because of past experiences I have a hard time opening up to people).

There's a coworker I've come to like because he tries especially hard to include me in conversations and get me to talk. He just doesn't give up. I very much respect this and am grateful, but its still hard for me to develop a friendship within the work setting. I want to ask him to hang out, but I'm afraid he's just being kind and isn't actually interested in developing a friendship. I'm afraid it would seem out of place to ask him to hang out when I've pretty much never started one of our conversations. I'm also afraid he might think I have a crush on him and want a date (which is not the case - I have a very serious relationship that is working towards the goal of marriage). I really don't know - Is it appropriate to ask to hang out outside of work? How would I go about it in the least intimidating way?