Hey @WorkingOnIt110
I see watermelon21 and Stormy_RO has already given you some great advice on their past experiences and how to cope with friendship breakups. As with watermelon21, I have also been in the same position as you and understand what you are going through. Unfortunately as a female friend it is very common to lose guy friends when they get girlfriends due to the stereotypes of "boys and girls can't be more than just friends" and the insecurities of girlfriends.
I know its hard but I would try not to judge the girlfriend too much for breaking up your friendship, there is a fair chance she may have insecurities based on past relationships/experiences with others that cause her to be uncomfortable with her boyfriend being close to another girl. If it's possible and you are around the couple within a group setting make sure to make her feel comfortable and welcomed, she may be uncomfortable with your friendship with her boyfriend as she is feeling left out/as if he is closer with others than herself, especially if the relationship is fairly new and/or you have been friends for a long time.
The engagement thing is a bit weird if no one else knows but it is possible they just haven't gotten around to a proper announcement yet, I wouldn't stress too much unless it seems to be something affecting your friend's mental health or happiness, then maybe a discussion with a close mutual friend of yours would be beneficial.
Otherwise I'd just recommend even if you cannot be close friends with your friend due to his girlfriend to just be a sideline supporter. Sometimes our friends go through things we cannot control and the best thing to do is just be there on the side ready for when they come out of what they are going through, as chances are they will need support/a friend afterwards.
I hope this helps and good luck with everything! Make sure to take care of your own mental health through this time as it can be hard on your emotions ❤️
