That Nagging Feeling...

You know that nagging feeling you get when you realize you might be giving someone the benefit of the doubt too often when in fact they're pushing the boundaries of your trust?  Yeah.  I feel like maybe I'm in that situation.  For whatever reason I have issues trusting people, but I'm also generally the trust-but-verify sort, and I try to assume the best until there is solid proof otherwise.  Maybe it's just denial and the attempt to hold onto things that aren't the best in favor of at least having something...idk.  The person I've been sort of seeing over the past few months is fresh into residency in another nearby city and I knew that going in, but I've seen other residents' relationships work out nicely with regular [albeit brief] communication.  Things have fallen into a pattern where he's generally good about calling or sending a quick text every day/every other day for a few weeks, and then there's a two or three week period of non responsiveness.  He'll eventually call and say he was on nights or sick and was just sleeping and working.  On one hand, I know the job is HARD and sleep deprived.  On the other hand, I don't understand why he couldn't find time to send a quick txt to the effect of, "I'm sick and swamped, call you in a week or so."  We've discussed it previously and I've said that he can call or txt me any time of day, since I leave my ringer on if I want to be woken/silence it if I want to get the msg when I wake up.  And for a while he does ok, but then there's that God-awful period of nothing.  We've also discussed me driving up on his day off or for a few hours when he's off, but he hasn't been letting me know when I can come up lately.  It's only an hour and a half/two hour drive, and I have the flexibility to make it happen, but it's creating a situation where I look forward to something for a long time and don't get a payoff.  I think it's affecting my sleep at night, b/c I'm waking up at various intervals and checking my phone to see if I've heard from him.  I feel like this is how it's going to be...I can't keep hoping or expecting for it to change.  I really like him, but I have the nagging feeling that I'm being a fool and letting him string me along when he's no longer really interested.  My bff says he thinks I should leave it open, but continue exploring other possibilities and not take it too seriously.  I feel like I can't talk to anyone about what's happening here b/c they are not understanding about why I like him so much.  It's difficult for me to be interested in too many people at once, and I'm finding that I have real difficulty with continual disappointment.  So I feel lonely, dissatisfied, and unable to make a change.