I got the impression that Rachel really wanted to be with Peter, but was afraid of his lack of commitment and also to go through this whole process and not being engaged at the end. So she settled for Bryan because his feelings were polar opposite of Peter's, which is ultimately what she wanted. I find it odd that the public flamed Ben for saying "I love you" to both Jojo and Lauren, yet Rachel said it to Peter while they were parting ways. Everyone felt bad for Lauren having to experience that afterwards, but no one has mentioned how Bryan is taking that.
I don't blame for Peter for not wanting to be engaged just yet. I think Bryan was more interested in the "winner" title and would have had the same feelings and reaction regardless of the woman in the role of "Bachelorette". Perhaps Peter went on the show open to the idea that he could fall in love and be ready to propose, and then he just wasn't there yet with Rachel. Just because you become a finalist in a few weeks time doesn't mean both parties in the relationship are ready for the next step. I thought his points were valid and give him credit for staying true to himself.
All of this said, when Peter point blank asked Rachel whether he was the man she wanted to be with for life, she said she couldn't answer that. Had she said yes, that may have swayed Peter. Who knows. I also found it odd that when he said that he would sacrifice and propose if that would make her keep him, she said she didn't want that because she knew it wouldn't be genuine. I respect her for not agreeing to that. But by not agreeing to that, there were no other options then.
Rachel said on Inside Edition (or one of those shows) that she didn't want any of her men to be the next Bachelor. That she felt possessive of them and that they should pick a guy from Jojo's season. Spoiler sites guess that Peter is the front runner, but the show is waiting until after Bachelor In Paradise to see who the stand-outs are, which is how they chose Nick last year. It's looking like Wells is back on BIP for a third time (yawn) and Robbie has been popping up a lot, so I wouldn't be surprised if he's vying for the spot too. They should go back to Luke!