When our partner is not interested in intimacy in few situations, we should not force them to do it. Because, it is in those situations, where your actual loyalty comes out.
It should be noted an intimacy with our partners should be out of love and through that love, a lust can be formed later. But lust should never overtake the love. If that lust is observed, then within no time, a different kind of thoughts starts rolling in the minds of our partners and that might even lead to the gap between the couple.
So, tackle the situation very carefully by making them know the importance of intimacy between the couple and then adjust accordingly.