The heart line is read as the emotional weather report of the hand. Traditional palmistry treats it less as a forecast of who you will love and more as a description of how you love — whether you lead with feeling or with caution, whether you say the thing or sit with it.
Where it ends matters more than how long it is. A heart line finishing under the index finger is read as idealistic and romantic — someone with a clear picture of what they want. Ending under the middle finger is read as more self-directed, driven by your own needs rather than a partner's. Ending somewhere between the two is the most common of all, and is read as the balance most people actually live in.
If yours is faint or hard to trace, that is not a verdict on your capacity to feel. Line depth varies enormously with skin, age, and how you use your hands.