It makes perfect sense to me. He's a red-blooded male and she waved something in his face he couldn't resist.
Look at all the times he got back together with her even after she slashed his tires (twice!), slashed his date's tires. Many months after he knew she was an obsessive stalker who got into his email and Facebook accounts, slipped into his bed or hid in his closet waiting for him to come home. Drove hundreds of miles to confront a girl he was dating; sent anonymous emails. And THAT was months after they broke up in the first place, for very good reasons.
Christmas 2007 - She slashes all four of his tires. The next day he buys four new tires. She slashes
those.
January 2008 - She sends him sexy texts on January 8 and January 18.
March 2008 - TA and JA visit several states together, including Texas and Oklahoma.
April 2008 - Several weeks after JA moves back to Yreka, TA sends her the following texts:
April 20, 2008 - TA texts JA: "I am at a night club right now and it helped me to come to the conclusion that you are one of the prettiest girls on the planet."
April 21, 2008 - TA texts JA: "Send me a naughty picture."
May 10, 2008 - TA texts Arias: "Why don't you have him come and f--k you in the woods, I can only imagine you are so worried about me reading. You are paranoid because you have no respect for people privacy and you dare insult me of all people. Someone you should through your actions you hate more than love by denying me a human right of privacy countless times. You have a lot of freaking nerve. We are all not like you in that aspect."
Around the same date JA records a 40-minute phone call in which they both talk dirty and talk about fantasies of things they'd do to one another.
Read it here:
http://transcripts.cnn.com/TRANSCRIPTS/1302/12/ijvm.01.html
Listen to it here:
http://www.huffingtonpost.com/2013/03/04/jodi-arias-trial-redirect_n_2808218.html#52_the-phone-sex-recording-graphic
May 26, 2008 - TA sends JA angry texts over something she has done, calls her evil and the worst thing that ever happened to him.
June 4, 2008 - While some go to great lengths to insist TA couldn't possibly have had a sexual encounter with JA that day, that she must have uploaded old photos onto his camera or taken the photos herself without TA's knowledge (
viz Occam's Razor) I saw a comment the other night that, to me, hit the nail squarely on the head:
"And I am sorry for the morally superior here. You show me a guy who turns down sex from an attractive girl when she waves it in his face. Go ahead. I'll wait."
(Someone responded she knew a lot of guys that would, but they were all in Rome atm.)
Timeline above excerpted from the following article:
http://www.huffingtonpost.com/2012/12/31/jodi-arias-timeline_n_2387245.html