Let’s clarify, because you are talking about having earned a position of trust and intimacy and being put off if your child does not trust you enough to ask your thoughts on this most important of all decisions. Fair enough–if we feel close, we might understandably feel hurt when there is a perceived rift in that closeness.
We’re not talking about your child talking about life decisions with you, although to be blunt it is a privilege to have an adult come to you with these things, and not a right, even when the adult is your son or daughter. Trust is earned, yes, but IMO it is a mistake to start thinking that a position of trust and respect entitles you to have a say with those who have come to trust and respect you you. After all, surely they respect and trust you because they have come to know that you will allow them whatever level of autonomy they choose to have. Parents who think they have a right to have a say-so have this way of eventually earning their way out of the decision-making loop.
No, we are talking about whether you have a right to expect your future son-in-law, someone whose trust you may or may not have earned, to ask you whether or not he has your permission to ask your daughter to marry him. Do you really think you have a right to expect that? You absolutely do not.
Your blessings and approval are yours to give or not give, but your adult children have the entire authority to decide who they will or will not marry and who they will or will not work for and where they they will or will not live, and no one else has any right to be consulted. If that doesn’t meet with their parents’ approval, then their parents’ approval is something they will have to learn to live without.
Still, I think you are only saying that you would be hurt if your adult child didn’t trust you enough to talk this over with you. Fair enough. That is a suggestion that the OP talk to her parents about her decision, not a suggestion that her future fiance do so.
Having said that, sometimes it is wise to give in to our parents’ expectations, even when they don’t have any right to expect what they are expecting, provided there is no real loss in adult autonomy by doing so. There is such a thing as dead right, LOL.

Seriously, though, it is a good habit to look for these little gracious gestures, when no harm is done to the marriage in terms of setting up an inappropriate sense of control in the parents. Consider it payment for all those future times when your parents will be biting their tongues to bleeding.