There's nothing like resentment, anger, frustration or hurt between two partners to dampen any kind of sex drive. Excluding "make up sex", if the issues run deep and are unresolved, this could be whats dampening your desire.
I think it’s always a good plan to have those “serious chats” when you are doing something else to occupy your mind. Not sat opposite each other intensely staring each other down. Or in bed at the end of a long day (trust me, not a good plan!). But maybe whilst going for a walk, cooking dinner or washing up. That way there is no awkward eye contact, and you both feel more relaxed. I broke the conversation with the boyf whilst driving. It was good.