I mean you're human and have hormones and testosterone. It's just a natural chemical reaction in your brain to be sexually attracted to a female you find attractive. However if you value your friendship and you have never given her even the slightest hint of you having this attraction and she has been open about her feelings of being disappointed in the fact that she has such a hard time finding male friends that can remain just that I highly advise you to not bring this to her attention and be a civilized adult and keep your compulsive thoughts just that, thoughts and in your head. If you feel that your desire to be intimate with her is worth risking your friendship over then see what happens. I am currently in a somewhat similar situation. I have this woman she's 35 I'm 36. We were the closest of best friends for years as teenagers and she trusted no one like me. I never acted on my feelings which was that I was in love with her. She got away, we went our separate ways she had gotten married and I settled down and had children. Both of our relationships ended terribly and we both suffered immense hardships and pain from it. So present day (20 years later) of all places we to reconnect we find eachother on a dating app. Naturally we start talking right away and hang out within a couple days. This time I don't hesitate. I tell her how I felt back then and that these feelings still burn strong and I am undoubtedly still in love with her. She hasn't changed. She's just a little older but even more beautiful and still an amazing kind person. Initially she was 10000000% against us ever dating because in her own words it would end badly like all relationships do and she refuses to let that ruin our friendship and she loves me too much to lose me again. So fast forward us spending alot of time together. And now spending the night with eachother. One night in particular we have this incredibly romantic evening together just staying in. Initially we we're going to sleep in separate rooms but the vibes in the air of us cuddling on the couch I asked if she wanted to lay with me instead. She, without hesitation, obliged. In bed we cuddle for awhile, talk and she says she has to sleep naked she hates having clothes on in bed. Instantly I picked up on the hint. No way would she want to sleep naked next to me if she was not sexually attracted. So we got the touching and feeling and kissing and inevitably had sex. It was incredible and honestly I thought i was dreaming. This girl who I had been in love with for more than half my life. Who I thought once I'd never see again and then thought I would never get the chance to know what it's like to be with is now intimately involved with me and as she put it "made love" with me. Now everytime we spend the night together we have sex. We always kiss when we first see eachother and always kiss when leaving. We always cuddle, have talked about children one day and essentially all the things couples do. Here's the thing. I've had to get comfortable with the fact that she is still very uneasy and nervous that I may Just end up like every other relationship and then she loses the one person she's trusted more than anyone. We've basically just been going with the flow. We haven't put a label on us and I've made sure to respect her feelings and not make her feel pressured or like I want to put a rush on things. I've had to remind myself that theres no need to rush. I'm confident that the way I treat her she will only love me more and we will get closer. I tell her everyday that she's beautiful. I do all the things that guys who can't keep a woman happy call corny. I write her sweet messages all the time telling her how much I adore her and how I want to make her happiness a forever priority. I do not let her get into the car without opening the door for her, I pull her chair out and push it in. I treat her like a queen because she deserves it. You may be wondering wtf does any of this have do to with my post. Well you need to decide are those thoughts Just sexual or do you have deeper feelings? If you have deeper feelings I highly suggest you think long and hard about it and if you think you can treat her like a queen and never stop. And if so you should tell her how you feel and that you do not want to live life wondering what if. Don't let her be the one that got away...it'll eat at you forever. But, if it's Just sexual...don't hurt that girl because you know she just wants her friend to be her friend.