I find him very subtly controlling

I have been living with my boyfriend for six months, and we have begun talking about marriage. We dated for two years before I moved in, and it seemed like a great idea because we knew what we were working towards. Things have changed since then, for reasons I don’t understand. Before I lived with him, he was more respectful and gave me space. After moving in, there was a shift that made me feel as if he is in control of this relationship and I am supposed to follow his lead. This isn’t something I can explain because it’s little, subtle, things that make me feel this way. I don’t know if I should treat this as a red flag about what he may turn into if we marry. How do I deal with this?
It is important to first try and pinpoint the subtle ways in which you feel disrespected, even if you don’t think of them as major issues. Shifts in power are common in any relationship, and the best way to deal with them is to arrest them when you identify them, instead of allowing them to become more pronounced. It’s possible that your boyfriend is unaware of things he is doing to make you feel disrespected, but that is not an excuse for his behaviour. If you want to marry, nipping these issues in the bud is the best way to draw boundaries and set expectations, because they will define how this relationship evolves for you both. Tell him why you feel slighted and insist on a conversation even if he doesn’t agree with you. He needs to acknowledge and accept that this relationship will not be successful without mutual respect.

My best friend is angry with my boyfriend and has been avoiding me because of it. What do I do?
Ask them to speak to each other like adults because they are both important to you. If they don’t, accept that it is their loss.