The fact that Jenna went into that last date wanting to have a talk to "define the relationship", tells me that she hoped, rather than believed, that they were exclusive. It strikes me that she asked a question, didn't get the answer she wanted, and was upset by that. I realise she didn't actually ask the question - it answered itself before she could - but it makes me wonder if there's any way that date could have gone down where she *wouldn't* have gone home unhappy. They want different things. That was going to come out regardless of whether it was via an unfortunately timed phone call from another date, or from a heart to heart conversation. I can understand her feeling hurt to hear the guy she liked didn't like her back the same way, but I hope she realises that's just part of life, better to find out then than further down the track. Unreciprocated feelings do suck, but he wasn't dishonest with her in any way.
Personally 4 dates in a month sounds like nothing to me - when DH and I started dating we saw each other nearly every night, because we were really into each other. If I really liked somebody I wouldn't go days without seeing them. Then again, I'm pretty decisive about these things. Maybe it's that aussie thing that LifeOnPluto mentioned - I know a lot of couples here who dived right in. Very all or nothing! I assume that there are people here who date casually though.