First and you have to make this seem natural you have to make her feel that you find her attractive. Sincere compliments on how she looks, even little things like "I really like how you did your hair today". Touch her, not grope her but hold her hand, put your hand on the small if her back when holding the door for her, a gentle hand on her leg while sitting watching TV together. Okay you can grab her ass some to when appropriate. Make love with her, often. When she feels you desire her she will feel desirable
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Okay it can be more complicated but it starts at home and with you.