Based on the information given, here is what I have come up with:
Key Players:
Samantha Weaver - Missing Person; Female, 27
Billy Jack Kirkpatrick (Ex-Fiance) - Male, Age ~28
Samantha's current boyfriend - Male, Age unknown, Identity unknown
Fact: On June 14th, Samantha went with a few friends to Riverwind Casino. Later that day, her friends dropped her off near a house in Shawnee.
Assumption: The location that she was dropped off at was the intersection of Wallace and Kickapoo. I'm assuming this is the correct location as it is the last place she was seen.
Assumption: She successfully made it to whatever house she was going to. The news article does not specify the details of this house. I'm assuming it was either her house or the house of the man that she was currently dating.
Fact: Sent two text messages:
a) 1 to her ex-fiance that said "I Just woke up, something doesn't feel right".
b) 1 to her ex-fiance that said "Im coming in a bit sweets I need you I think I missed a lot while asleep"
Fact: Shawnee police believe the primary suspect is the man she was last seen with.
Possible Scenarios:
1) Samantha was murdered by the man she was currently dating. I think this is the most likely scenario. She probably went to visit this man after her casino trip. Subsequently, she awoke after a nap and got in an emotional argument with him. As a result, something happened, whether on purpose or by accident, and she was killed. To try and cover up the tracks, this man hid the body.
2) Samantha was abducted on her way to the ambiguous 'House'. This is probably unlikely. Although she did not live in the best area of Shawnee, I still don't see an abduction like this happening here. What would be the motivation behind an abduction of a 27 year old mother? I could see potential for a 17 year old teen, but not a 27 year old mother.
3) Samantha was abducted on her way to see her kids. Same comments as option 2.
4) Samantha was murdered by her ex-fiance. This is pretty unlikely as her ex-fiance has been quoted by the media as being very concerned over her disappearance, but this still should be mentioned. What if she arrived at his house to see the kids and got in a heated argument with her ex-fiance. I'm assuming they are no longer engaged for a reason. And was there some sort of custody battle going on? Hard to tell from the outside looking in, but I'm sure the family, and hopefully the police, know the details.
5) Samantha was raped and murdered by a local admirer. This scenario is out of left field, but I figured it was worth a mention. Since Samantha frequented the Sinclair gas station at the Kickapoo and Wallace intersection, she probably knew the employees and possible the other frequent customers. Since she was last seen at this intersection, maybe this 'admirer' abducted her, knocked her out, raped her (hence text message 'I just woke up, something doesn't feel right'), got in a shockingly emotional argument, and subsequently left in a panic to find her ex-fiance (hence the text message 'Im coming in a bit sweets I need you I think I missed a lot while asleep'). I think the logical thing to do would be to call 911, but due to the shock, it may not have entered her mind.
Additional Thoughts: I think the Shawnee police are pretty sure they know what happened, but they do not currently have a strong enough case to convict the suspect. They would probably need to find her remains. I suppose they could also try to build a case via testimonies. Regardless, this is a very sad story and I hope that someone can find some answers.