When I got into buddhist meditation, I was in a major depression. Regular meditation practice helped me with that - it made me a lot calmer. And for quite a while, it was good. Very good, actually.
Now, most buddhist writers (and speakers) place a lot of emphasis on being here and now, not blindly following the fantasies, slowly disidentifying from the "monkey mind", the "mindless mind chatter".
So, ever so slowly, while becoming calmer, I also got more disengaged from some of my old thought patterns, some of my old feelings. That was good, because it was bad feelings and destructive thoughts that got me depressed in the first place.
But at some point, I realized that I had gotten more than I had bargained for. I had lost some of my desires. But did I actually WANT to lose them? Among those desires was my desire to write good literature (in my mother language, of course, don't you worry!). But I didn't realize that there might be a connection; I just assumed that it was one of those naturally occurring periods in which I didn't fancy writing so much. And writing had often been connected with intense suffering, so actually, that felt pretty good, too. So I had no motivation to change that, I assumed that it would just come back at some point (as it always had), and anyway since I didn't know what was going on, I had no way of changing it either.
A while later, I got into tantra. I learned how to create ecstatic feelings at will. And for quite a while, it was good. Very good, actually.
Now, tantra places a lot of emphasis on being here and now, not blindly following the fantasies, instead focusing on deep breaths and utterly slow motions.
That was good, because it made me feel happy, and there's rarely a guy out there who couldn't use some slowness and endurance in their sex.
But at some point, I felt my sexual desire floating away. Not that it felt bad - it was just weird, and slightly astounding. (Maybe I should tell you that I'm basically horniness incarnate. I cannot remember any time before that - after hitting puberty of course - when I didn't want sex. Not. One. Day. Seriously.) I thought it might just have to do with getting older and thus, less flooded with hormones. So there wasn't really a lot I could do about it, and as I said, it did feel really good in a way, so I let it go.
But a week ago, I got back into my old habit of keeping a dream diary, and then a few days later, I started reading a book on daydreams. Basically, it's about how they're a good thing, how they are necessary for any creative effort, for planning, for building a life.
Then it suddenly hit me: I have basically made a habit out of treating my daydreams with disrespect. I was always a rather introverted kind of guy, I enjoy having a conversation with myself in my own mind, I like building inner-world universes. If I don't treat my fantasies right, of course I don't get what I want! Of course I lose my creative spark.
So I'm rebuilding my daydreams now. I'm keeping a daydream diary along with the night-dream diary, and I consciously build up those sexual fantasies again.
Not that I'm blaming anyone, or whining around. I took this upon myself, and now I found another detail, and that is excellent. It's just one more part of my journey.
I just feel that those experiences need to be shared, so that, if you plan to delve into some form of meditative practice, you know that something like that can happen to you. It's not necessarily bad, either - just something to watch out for. If you feel that your fantasies are overwhelming, and they're giving you a hard time, then that's exactly what you want: some distance. If you're low on energy and in a constant mellow state.. probably not so much.
I think the bottom line is that meditation, tantra, etc. are all tools. Excellent tools. But they're not perfect, they're not ends in themselves, and as with any tool, using them has a downside that one should be aware of.
And never never never never EVER let anyone tell you that your daydreams are a bad thing, filthy, sinful, or something to be avoided. (Of course, there is something to the buddhist perspective that you shouldn't identify with your thoughts, and of course, this is yet another tool that has other downsides that I'm not seeing yet... but... it's complicated. I'll say more about it once I actually know what I'm talking about.) I say honor your daydreams, treat them with respect, hone them, nurse them, water them like beautiful flowers. They deserve your best, and they will pay you back what you give them, interest and all.