Male libido

Patient: Please 26yr old partner has lost his libido, completely. he tells me that before we met that it was completely normal and for the first 4 months that we were together everything was normal but then it just stopped, there has been nothing since and we are coming up to the 3yr mark. he had blood tests done but everything came back normal. he tells me he just ‘doesn’t feel like it’ what can we do?