Advice columnist and relationship expert Matt Whyman answers:
Sometimes people find it difficult dealing with illness. Just as you might find it challenging, it can also affect those people who care about you.
Taking the pressure off
Lucia was diagnosed with cancer 10 years ago. She says: "Cancer can put a big strain on a relationship, but this doesn't mean it's over and that things can't get better."
The emotional effects of facing cancer and the treatment could cause you to have mood swings that your girlfriend might not understand.
It might help if your girlfriend talks to your nurse about your medical situation. This takes some of the pressure off both of you. Your girlfriend can ask questions and you won't have to go over every detail about cancer and your treatment.
Be open and honest
When you're ready to talk, as in any relationship the key is to be open and honest about any issue on your mind. It beats keeping your worries to yourself and gives you both every opportunity to address things constructively.
Find a quiet, calm time. If you're in hospital, ask the staff if there is somewhere you can talk privately. Start with a chat about how the relationship is doing and give your girlfriend every chance to talk. This way, when you address your concerns it'll be just one aspect of a wider conversation.
Keep an open mind about your girlfriend's response, and be sure to have someone you trust on hand should you need a listening ear. Whatever happens, you'll be taking responsibility for the situation.
Dealing with concerns
Young people's community worker Bethany says: "A lot of people are scared of talking to someone with cancer, as they don't want to upset them. Let her know what she can do, practically and emotionally, to support you."
Urvashi Tripathi, a senior social work practitioner, gives this advice: "If you are not doing the same things that you used to in your relationship, maybe she worries about putting you at risk if you are unwell. It is best to be open and to talk to your girlfriend."
Content added: November 2015
Review due: November 2017