I guess he missed this: "I was nothing more than a dildo with a heartbeat for you,"
http://www.huffingtonpost.com/2012/12/31/jodi-arias-timeline_n_2387245.html
For me, that pretty much summed up their relationship and something that a young man trying his human best to follow the dictates of his religion would already be beating himself up over and therefore would not likely be a "guys are like that" kind of guy, no matter his verbal flirting.
Travis did lots of casual verbal flirting, and he went beyond that, verbally, with several women, and maybe even beyond the verbal as well, though if texts capture his activities, not between Dec 07 and March 08.
I think I know what he was saying to her with the dildo-heartbeat acusation, but IMO, it is no more accurate to say the killer used him for sex than it is to say he used her for sex. Travis told her that in the May 26 text because he was just trying to figure out what she wanted from him, why she so obviously was trying to destroy everything that he held dear.
The part that Nurmi doesn't understand, or won't admit to understanding anyway, is what you bring up about how guilty and conflicted sex made Travis feel.
I quoted upthread a very sad text exchange between Travis and Taylor. In it Travis states explicitly that he feels extremely lonely, even "numb," which I read as feelings of emptiness. He tells Taylor he has fun being a player, but that as much as anything, what he's trying to do with those pursuits is simply to make his pain go away.
Nurmi read that text.
Nurmi also knows that Taylor has said Travis was extremely angry with himself for getting physical with the killer after she moved to Mesa, even to the point of telling Taylor he hated himself for it. Nurmi knows that all of T's friends have said his faith was core to who he was, that he credited his successes and even his life to that faith.
Nurmi knows that.
Nurmi has read all the texts between them, viewed the phone logs of both, read her journals which so contradict what she tells Travis on any given day. He knows she lies. He knows that the killer was obsessed with Travis. He knows that she knows enough about Mormonism to know how conflicted Travis would feel about having sex, and he knows how much effort she put into throwing herself at him. And he has years of first hand experience in how manipulative she is, he's even listened in as she's convinced others to do her bidding.
Nurmi knows all that. Can he really be so incapable of understanding the plain as day reality that Travis didn't use her for sex, and she didn't use him for sex, rather, that she used sex to control him? The worse he felt about himself, the more self-doubt and sense of self-failure he felt, the more vulnerable he was to her. She wanted to destroy him so she could possess him entirely.