I mean, to be fair though I feel like it wasn't exactly that straightforward in him being intentionally manipulative though. I think he's indecisive, frustratingly so.
For that conversation, he didn't outright say what you wrote. He said he loved her so much that he was ignoring his instincts and would propose even though he felt the timing wasn't right but he believes she was the right person. The whole resentment issue was something she brought up and even then, he said he hoped not and he hoped he was mature enough not too, but he was an emotional person. That reeked of indecisiveness to me rather than someone trying to manipulate the situation. He keeps going back and forth which doesn't show a lot of confidence in anything.
The ring thing I wish there was more context because someone said he did give her a ring as gift, which was one that she wore to that final date. I'm curious if it was in context a specific wedding ring question, a ring as a gift, or even a future conversation similar to his first date where they talked about if either would be willing to move for someone (while a valid topic, not necessarily immediate/near future). Considering how much she wanted a wedding, he should have been more careful with his words if that wasn't the case but even then, I viewed it as similar as that first date conversation where just knowing the information wasn't necessarily a promise to do so.
I can't necessarily view him as manipulative because I honestly don't get the feeling that even he knows what he wants. He seems to go back and forth so much that I feel like he means it in the moment, but then he changes his mind (similar to the whole will he won't he be the next lead).