Become a Redditor and subscribe to one of thousands of communities. Maybe in a Facebook album somewhere? Obviously this conversation will go a lot better if you offer to go with him and get tested at the same time. We also have a chat, just for us. I've told him that I have feelings for him, and he says they're reciprocated. Yeah, I know you don't want to, but cold turkey really is the best way to get over these things. I have two other sets of friends that are now in long term "real" relationships that evolved out of casual ones, so it definitely happens, although I suspect it's not the norm.
You could start by reading the signs, though, to see how casual your casual relationship is.
6 Signs That The Person You're Dating Wants Something Serious
It took about seven months and my second visit to Iceland for this "friendship" to coalesce into a relationship. One thing to look out for: Any tips on how I can do this? If YOU want a relationship, you should go for it. Long story short, the first date went extremely well ended up going back to my place and making out after spending nearly 6 hours together. I had one of those 'casual' relationships for about 4 months before we officially started dating.