Hi there! It sounds like you and your boyfriend are going through some tough times in your relationship, but I'm here to offer some advice.
Firstly, communication is key in any relationship, and it's important that both partners feel comfortable talking about their feelings and concerns with each other. It's understandable that your boyfriend may not want to talk about certain things when he's feeling stressed, but it's also important for you to know what those topics are so that you can avoid bringing them up.
At the same time, it's important for your boyfriend to recognize that bottling up his feelings may cause more harm than good in the long run. Encourage him to find healthy ways to manage his stress, such as exercise, meditation, or therapy, so that he can better cope with difficult emotions.
Regarding your past relationships, it's important for both of you to recognize that everyone has a history and that it shouldn't impact your present relationship. However, it's also important to recognize that everyone has their own insecurities and triggers, and it's okay to set boundaries around certain topics. If talking about past relationships makes your boyfriend uncomfortable, then it may be best to avoid that topic for the time being.
Lastly, remember that relationships take work, and it's okay to disagree sometimes. It's important to approach disagreements with empathy and understanding, rather than defensiveness or anger. Try to listen to each other's perspectives and find compromises that work for both of you.
I hope this advice helps and that you and your boyfriend are able to work through these challenges together. Best of luck to you both!