I would recommend that you start with his online quiz to find out which is your Love Language. The five types are: Quality Time; Touch; Acts of Service; Words of Affirmation; and Gifts. People tell me the quiz itself is not great, but the outcome is valuable enough to do it anyway. Also, you can skip the part where they ask for your email address.
Our Love Language is what we most need to feel loved by our mate. However, we tend to give to our mate in our own Love Language, and therefore we may be missing a huge opportunity for her to feel loved by us.
Some couples have the same Love Language, many do not. Practice giving to him in his Love Language for a while and see what happens.
If your Love Language is touch, then also holding hands, cuddling, kissing, and passing touch can fill your "love tank," as Chapman calls it.
What did you do together when you were first dating? You likely gave to each other in each of your Love Languages, and now, for whatever reasons, you are not. So go back to doing what you did while dating.
I also recommend that you read the book, as he does a great and simple job of explaining the chemistry of the brain, transitioning to long-term relationships, and generally helping couples understand and learn from their issues.
My one caveat: Chapman's book has a distinctly Christian tone to it. As with any suggestion I offer; do with it as you wish, take what's useful and leave the rest.
My clients tell me that giving and receiving in their own Love Language does not resolve their issues; it brings down the tension level in their relationship so that they can learn about and work on the actual issues.