Shes destroying my head?

ive had this female friend since i was in my early teens and now in my late thirtys ,we both have partners and still close even closer friends.ever since we met whenever we socialize with alcohol its like we cant wait to get together and talk and we always do at some point and usually about our lifes and deepest thoughts and ends up about our feelings for each other and usually ends up with us clearly admitting that theres an attraction and that she is inlove with me but cant have me because we have partners and at she always has been(we get very intimate about our feelings towards each other and she always brings up that she wished that i had dated her when we where in our teens .SHE ALWAYS BRINGS UP NICE THINGS IVE SAID IN PAST CONVERSATIONS SO SHE DOES REMEMBER, but usually after these sort of nights i wont hear from her for a couple of weeks as she avoids me and when we do see each other she is quite sheepish for a while and them comes round to being relaxed again and at times i want to bring it up as it stuffs my head up but when i see her she acts totally as if nothing has been said and is totally different person and i strongly feel if i said anything she would totally deny it and i feel she would make a scene.then as soon as we have a few drinks we start again.she is not like this to anyone else.whty she doing this and what do i do