Three months is not a short time and we only have OP telling her what her son told her.
We have no idea if the gf brought it up again after that.
The gf wanted a proper discussion about it and he brushed her off. Just a discussion. Not ‘are you going to marry me now’ but to discuss plans for the future like the majority of couples and he couldn’t even do that.
If you don’t know if you want to marry the person you are living with after three years of being together, don’t even want to have the discussion, or even say I want to do xyz before marriage, then you either don’t want to get married or you don’t want to marry the person your with.
He could have easily said something instead of the answer he gave her. They had been together long enough for him to be honest about his feelings instead of dismissing her which tbh is an answer in itself.
His actions have only shown not only is he not ready, he isn’t mature enough for marriage.
If he was, he would have had the conversation.
My DH and I sat down and had the discussion before we were engaged, right around Christmas. We talked about marriage, children, how we saw the future, and we were on the same page. He proposed to me in the summer after that talk (he didn’t have the ring at the time and had just blurted it out while I was telling him something ) and we were married the summer after before my 26th Birthday. We had been together just over 2 years by time we married. It didn’t feel like a rush to us and we didn’t live together until we were married. Been together for 14 years.
If you know, you know.