"ในร่มเงารัก" means under the shade of love. 'ร่ม' actually means 'umbrella' or 'shade'. In this context it means when you are stay under the shade of love, you will feel more comfortable in your heart. "ม่านบังใจ" means curtain/obstacle that conceal the heart. 'ม่าน' actually means 'curtain' but in this context it literally means 'obstacle' which shades or hides or conceals you not to see it clearly or your true heart.