I've been married for the past year and a half to a guy I met online and have not seen for about 4 month after we started talking. We had a long distance relationship for almost a year before I finally moved from Israel to New York to be together. I know other couples who this happened to and I'm sure this will just happen more and more.
So, as for your first question - yes, it happens and it works! at least for some people.
As far as bored - I don't think a relationship is about entertaining one another, I think that if he would find you boring, he would find you boring in reality or online, the medium really doesn't matter. I think that to keep things going and to make the relationship a good one, it's really important to talk a lot and to talk often. We used IM and had web cams and we basically had them on all the time, we'd watch each other sleep and have meals together and just spend a lot of time together, which is a good thing for any relationship. We actually used this time apart to built very good communication patters based on words and honesty, because when it's an on line thing, you can't escape to sex or fix things with a hug or a kiss. 5 month is a long time, but if you are serious about it and if he is, you can totally make it work for you.