Lower libido and excitement in sex

Last 3 years my libido is lower. I am 32. I dont have kids yet. I have stable partner for almost 7 years but our sexual life got worse. Not sure what was first, my lower libido or less frequent sex. Not sure if this is partner problem or something different. It just feels like I lost interest in sex in general. I dont think about it much and I dont care for other men either. I feel like I am not good at it with my partner, otherwise I would be more excited for it right? :D