it sounds grim but, especially in this era of dating/relationships, I think by age 25 you learn not to put so much stock into what people say.
If you’re someone who does what they say, it can be incomprehensible that anyone would do otherwise. However, you’ll find that many people are cowardly when it comes to this, because they can’t reconcile they’ve done or are doing something that ends the relationship.
This is what he’s done. You can evaluate his intent by his action, which is getting a vasectomy. You can continue to respond to people, that he said he wants kids with you, but you’re not evaluating his actual decisions, or plans. For example, does he put money away for a kid, right now? At his age, if he is planning on adopting (saying he is willing is not planning, and you two are in different life stages when it comes to being able to accurately create a life plan) he would be saving now. His life his half over.
As someone who did what he did (and has a clear idea of how I want my life to go), the fact that he’s (potentially) spending money to become sterilized should be a big clear sign that he’s not going to want to spend money on actual children.
What you have to decide is what you roughly would like your child-raising years to be, and ensure that he is actually taking actions towards achieving that. And if he says “after I’m 50” then you better be prepared to do most of the heavy lifting.