For about three years I was in the baal teshuva world, spending about two of those years in yeshiva. I came to be religious because of "spiritual" experiences, which may have been prompted by unmet emotional needs. When I was in yeshiva, I was told that you could rationally demonstrate (not "prove", sort of) that Judaism is true (and so, I reasoned, that there is a God). After working hard on these pseudoproofs for a while, I became convinced of one. I then believed very strongly that God exists, that He loves me, and that the religion was true.
For some time (days, a week?) after arriving at this conclusion, I felt incredible. More in love than I ever felt about a girl. When they say you should have a passionate love for HaShem, that's what I had. I couldn't sleep - I woke up ecstatic - overjoyed that there's a good, caring God who is looking out for me, helping, etc. One thing I always wanted from a woman was flowers. I've given lots of people flowers, but no one has ever given me flowers. I guess that's just how it is in society. But when I felt this way, I walked the streets and viscerally saw all the flowers as being from HaShem. Not in an intellectual way - it was as emotionally real and believed as if it was from another person. Trees upon trees full of beautiful flowers. I also really love singing. And in this state, I could sing more deeply and passionately, moving the people around me to tears, than I ever have.
About a year after this experience, I left yeshiva and the religious world. I'm still not exactly sure how it happened. I think I realized that I'd come to the religion for emotional reasons, but it really wasn't going to help me with them (in many ways it made my problems worse). That peak experience seemed to be the extent of the love, safety, and acceptance that I was going to get. My doubts about the truth of the religion - scientific issues, immoral behavior of the rabbis, and the whole thing just looking as fake as any other religion, came together. Intellectually it's pretty clear to me now that Judaism is made up and that there is no God.
But I find it hard to let go... at least partly because of the experience that I had of feeling so in love and loved. Even if it was fake, I can't see how I could ever feel that way again. A woman would have to fill a football stadium full of flowers to top that experience. "Maybe one flower from someone real who loves you would be better than a million fake ones," you might say. But I believed that it was real when it happened, so the enormous love felt completely real then. How can I go on in life knowing that I'll never feel that way again? Has anyone else experienced this? How have you moved on?
I never really felt that way to begin with, perhaps because I was born and raised frum. I know that I admired and was drawn to various BTs I knew because I sensed that joy in them, but I never really felt it myself.
I'm not sure what advice I can offer except that I suspect such feelings are always temporary, like the infatuation period early in a human relationship. You don't need to be infatuated with (the idea of) God any more than you have to be infatuated with a human being to be happy. Maybe you can love the universe like you can love a human being after the honeymoon period wears off.
I think most people need to go through some kind of grieving process after they leave religion. Some miss the perceived connection with God, some miss the community, some miss the rituals, and some miss the sense of purpose, but we all have something to grieve.
I suggest psychotherapy for anybody leaving Orthodoxy. It's a traumatic experience even if it's the right decision for you. This is doubly true if you have other emotional/psychological issues.