My boyfriend of 5 years is 13 years older than me. We've had these quiet patches too. It becomes very important to realise when this is happening, and talk about it. Be careful to time the conversation well. Both of you need to discuss your wants, needs and desires.
If there's true love in a relationship, both parties will be striving to make the other happy, and they will listen intently to the conversation.
I'm glad you've both decided to go to therapy - that's a great step forwards!