JR's intent to marry Kimberly was the same as his intent to do a lot of things where other people were concerned, he strung her along with no intent to follow through with his plan, simply planning to swoop in and take control of what he was really there for before he had to go through with it. He was naive enough to believe that despite Sue Ellen's character development she was still the same mild mannered lady, prepared to look the other way even if it tore her up inside, ready to welcome him back when he paid attention to her again. This time she wasn't. Sue Ellen spent years developing, growing, changing and becoming stronger, she didn't need JR the way she had in the early years, she had her own fortune, her own life and confidence to go out on her own if need be. JR planned things to go a certain way but those plans backfired on him in a way he didn't expect. Kimberly's father died prematurely, Sue Ellen didn't divorce him, and when he went in for Weststar he was not the only interested party. JR was cocky in expecting he would always come out on top, he got that way because usually that's exactly how things were, not this time though.