Cancer can tend to another's needs like nobody else. You have nurturing down to a science. You prefer to control the strings and are happiest when a partner just goes with the (your) flow.
Stop and try to be objective. Are those claws pinching your friend just a little too tightly? Is he or she gasping for more breathing room?
If you have a tendency to expect disappointment, you know what they say about self-fulfilling prophecies. Ease up just a bit and believe in the process.
And don't bring up wedding dates or kids on the first date!