Why does it feel awkward talking to my mother about anything emotionally

Context:she changed so much after meeting her fiancé I honestly do not know what happend there. But now she’s so weird to talk to and I’ll be honest it feels like I don’t know her and she’s just a casual friend. It’s really sad Becuse every time I try to bring something up like this she gets really pissed off. Please tell me someone else going through this or knows someone that has.