All perfect praise be to Allaah, The Lord of the Worlds. I testify that there is none worthy of worship except Allaah, and that Muhammad is His slave and Messenger. We ask Allaah to exalt his mention as well as that of his family and all his companions.
Indeed your question comprised two matters:
The first matter: The reality that you are living with your wife.
The second matter: Your love for that woman.
There is no doubt that it is more appropriate to look into the matter of your marriage first. It appears from your statement that your wife is not interested in satisfying your affectionate desires, like beautifying herself and so on. We think that being frank with her in this matter is the best cure. Choose the best time and circumstance and sit with your wife to discuss with her so that she understands what you want, and act according to it. The wife usually responds when she knows that her husband is interested in what benefits her. We do not think that you should refrain from being frank with her about this matter. However, if you cannot do so, you can provide her with a cassette or material regarding marital rights.
We should note, however, that the husband could be the reason for his wife not being interested in him. Praising the wife for any good conduct urges her to do more good. The husband making himself attractive for his wife is also another means. Ibn ‘Abbaas said: 'Indeed I like to beautify myself for my wife in the same manner that I like her to beautify herself for me, because Allaah says (interpretation of meaning): {And women shall have rights similar to the rights against them, according to what is equitable}[2:228].' This is in relation to the first matter.
As regards the second matter, the answer is that if a Muslim man loves a woman, he still should not behave with her in a manner that displeases Allaah, like looking at her and the like. Since you are as you have stated, then All perfect praise be to Allaah, and continue to behave in the same manner. If you want to marry her, then there is no harm if you are able to provide for her and be just with her as a second wife. Indeed in Islam we are encouraged to marry more than one wife for great benefits. If getting married to her is made possible, may Allaah bless you, otherwise, you have to stop thinking about her, to avoid temptation and committing adultery.
Finally, we draw your attention to the fact that it is not permissible to shake hands with a marriageable woman, as this was the Sunnah of the Prophet . So you have to be careful not to shake hands. Please refer to Fataawa: 81433 and 84011 for the ruling about shaking hands.
Allaah knows best.