The feeling of being underestimated is sure to be felt at some point in life but you know what, it tends to have it's advantages. Being underestimated can be the fuel you need to light a new, stronger fire inside which will give you the power to go even higher and get things completed.
Just remember not let anyone deter you from finishing what you started trust in yourself 100% under any circumstances.
There are indeed two sides to every emotion. If you reward your lovers positive attitude with gratitude, they will present that same feeling again to you (and if they don't they are definitely not the *one*). Showing others who one really is without exaggeration or deception is paramount in any good relationship.
People like this will slowly drain you of the energy it takes to make a relationship work, (and lord knows it takes a lot of time and effort to make them work) its just not possible for a relationship to be in a good place if the significant other is constantly draining you with issues and constant complaints, fact is this type of lover won't stop until you and the relationship have completely run dry. Never give people permission to suck you dry, make it known that such actions are unacceptable and you will not stand for it.
Who couldn't use a well placed compliment? Compliments often make your partner feel good and everyone loves to feel good, plus it shows that you care (caring is a good thing!). Keep it genuine and never be afraid to speak from the heart. Love is a genuine compliment.