I'll piggyback on this thread because I can relate quite a bit. It took me a long long time from when I was younger in my teens observing that I might feel different about girls/guys than most of my friends, to my mid twenties when I finally came out.

I had a pretty textbook straight dating history up until I graduated college- I had boyfriends in high school, lost my virginity at 18, had a number of flings/hookups, and had a long term boyfriend. I've always gotten along easily with guys in a platonic sense, but sex was a major challenge. I didn't love it or crave it. It was interesting at times and enjoyable every so often but I wasn't a fan.

After my boyfriend and I broke up I went into a pretty deep depression and it took me years to rebuild. Over the course of about 3 years I basically went line by line down a list fixing things that fed my depression. Substance abuse, strong feelings of inadequacy due to not knowing what I should do with my life, getting back into competitive running, and so on. About a year ago, I felt like I had fixed the last item on my list but there was still something lingering.

I had always known I liked girls, but never acted on it or even really let myself acknowledge that I had a sexual identity that wasn't "straight". I figured, I liked guys enough and could tolerate sex, so having a less fulfilling romantic life was worth being able to live like a normal person. I was wrong. All of that repression really hurt me after all. The enormity of condemning and disapproving and repressing something so fundamental for so long really hit me about a year ago and I started very slowly coming out to myself and then others. It's made a world of change, I'm so much happier and at peace than I can ever remember being. I no longer feel the emotional fatigue that comes with keeping a secret.