https://www.cbr.com/did-spider-man-s...married-woman/
I'm going to assume the writer implied that they did
"He's pure power and doesn't even know it. He's the best of us."-Matt Murdock
"I need a reason to take the mask off."-Peter Parker
"My heart half-breaks at how easy it is to lie to him. It breaks all the way when he believes me without question." Felicia Hardy
Betty isn’t crazy. What she went through with Ned, her brother, working under Jameson’s anti Spider-Man propaganda, and Peter’s flaking when she needed him combined with her lack of confidence allows for most of her stories to make sense. Modern Betty will have struggles with all the hobgoblin drama but she’s grown as a character. Peter and Betty love each other in a plutonic way, understanding they enjoy each other the most as friends.
Mary Jane’s flexibility with social situations, work, and experience with spider drama is why it’s hard to find a better love interest. Betty, Liz, Carlie, and most of the grounded characters have too much responsibility and needed structure to be successful.
Even if Felecia love’s Peter Parker as much as spider-man. Peter too grounded in a normal day to day world for her.
To answer the OP, Betty has a kid. That's why she's out of the running as a romantic interest. If Peter can't be married because "it ages him", I think it's fair to say that Spider-Step-Dad ages him more.
Forget Betty/Peter romance.
But should Betty be let in on the secret of Spider-Man being Peter?
I think it would be good and make sense, but it’d just lead to a hostage scenario and Peter’s fear coming true. I mean sure, you can tel her, but what do you do with that? At least Jonah has had some fun moments where he harangues Peter and gets pissed at him for not doing what Jonah thought he should do.