Chemistry is actually a projection of both of your personality traits that overlap. In reality, chemistry doesn’t change, love does! You either grow to love each other more and try to build chemistry or your love fades away and you don’t care about the chemistry. There are ways to build chemistry but that can work only if you both still love each other as much. However, limerence or infatuation does fade away with time which diminishes the effect of chemistry. So, you must try to prevent the chemistry from fading with clear communication and respect.