honesty, devotion, similar interests, kisses, relationship, sex, making love (not the same as sex), communication, trust, not 50/50 (not 50%)
Honesty - Be honest with your lover. Tell the truth, don't keep secrets. Give him/her every reason to trust you.
Devotion - Love him or her and love only him or her. Don't have another person in your life.
similar interests - To have a strong relationship it helps to have similar interests. I love hiking and camping, I enjoy kayaking, riding horses listening to music. I don't smoke and I don't like to drink much beer or wine. I should seek someone who has "similar interests" or likes the same things I like.
kisses - If you don't know what kisses are ... your in trouble.

Good kisses are very important to me! Slow, long and then passionate.
relationship - This is the feelings between two people. You can have a business relationship with your co-workers and your customers but here we are talking about a relationship between a boy friend and a girl friend or husband & wife.
sex - Sex is the fun stuff we do sometimes and it is between a guy and a girl. It can be hot and full of passion but if your just having sex then it isn't about "making love" (see below).
making love (not the same as sex) - Making love is similar to sex but it is between lovers. It is a chance to express with your body how much you love and respect your partner. Both sex and making love can leave you sweaty at the end but only "making love" will leave your partner knowing you love him or her truly.
communication - Communication is very important to a relationship. Talk to your lover about what is important to you, what is on your mind. Don't share every complaint you have, it isn't about that, it is sharing some complaints but also it is a chance to tell him or her how much you appreciate the things they do for you. Secondly, it is a chance for you to listen... not just hearing them talk but really listening to what they say. They need you to hear them and perhaps there is something you can do to help your relationship.
trust - What is love without trust? This is the foundation of what love is built on. You must trust your partner, your partner and you must be honest to each other. Trust is believing in what your lover tells you.
not 50/50 (not 50%) - You cannot expect a relationship between a man and a woman to be 50/50. You cannot expect that you will only do 50% of the work and your lover will do the other 50%. It never works this way. You should understand in a relationship that you will sometimes do 80% of the work and your lover will only do 20% and at other times you will need help from your lover and expect them to do 80% and you only do 20%. I'm not talking about "work" like your job but I am referring to communications, trust, listening, etc.
I hope this little bit of vocabulary will help your grow the conversation about love in English.
Chuck