Remember the words from an old song...
"Be sure it's true when you say I love you, it's a sin to tell a lie".
The concept of "sin" has lost its meaning for most in our modern era, and even "love" has lost its importance.
If you still believe in "falling in love" then you will realize how difficult it is to say, "I love you" in a meaningful way. Three little words that could change your life forever. The words, themselves, have lost their meaning because of overuse especially when it's not really true. Everybody says them.
However, when you want tell your partner of your love it's such a hard decision to make for many reasons. Will your partner return your love? Will your partner simply accept your declaration with indifference? Will he or she feel threatened? It is such a common problem that even "The Seinfeld Show" had an episode on it.
So make it easy on yourself and plan the declaration so that as much as possible you eliminate the problems. The first step, of course, is to be certain you really are in love. If you so enjoy being with your partner that you want to be with him or her to the exclusion of all others, if you think of him or her every day when you are apart, you are probably in love. If you have even a small doubt you should wait a little longer.
If you are certain then plan a special occasion for it. Make it a significant moment in your life - one to remember with fondness for your whole life. Arrange an intimate dinner at your favorite restaurant and make it as romantic as you can. Give him or her a small gift because you love being with them, or you are so glad that you met them.
After dinner while holding your partner intimately gaze intently into their eyes and say, "I love you so much it hurts when we are apart. I hope that we can stay together forever".
Do not be disappointed if your partner does not return your declaration. They may not yet be ready and might need more time to state their feelings. Continue to share with your partner the highs and lows of your partner's life. Care for your partner's happiness and be on guard to protect his happiness.
Under no circumstances should you ever ask your partner, "Do you love me"?