I broke her heart and she didn't deserve it

Before I get into it, I apologise if this is the wrong instance for this post, I'm pretty new to Lemmy and I haven't managed to find something for break-ups.

For a bit of context, we met in February of this year on OK Cupid. We hit it off, chatted for a few weeks, then met up for a date. Things have been lovely with her. She is smart, funny, caring, compassionate, gentle, pretty, coquette, witty, and the list can go on. Bottom line, I really liked this girl and it wasn't at all hard to begin to fall in love with her right from the start.

I'm in my mid 30s, she's in her late 20s (6 year gap between us), we've had some minor moments of misunderstanding, we discussed things calmly and openly each time and reached mutually beneficial solutions, it was great overall. The only major aspect was the fact that she'd been sexually assaulted by past boyfriends. But we discussed this relatively early on as well, I told her I have no problem with waiting and I meant it, and we agreed to take it slow and just get to know each other. We went on to date at least once a week ever since. I had an awesome time with her, every date was enjoyable and I could feel us becoming really comfortable around one another.

But something started feeling off 3 months in. The dates were still awesome, I still enjoyed spending my time with her, but I started feeling awkward when kissing her, like I didn't really want to. I chalked it up to a rough patch in my own life which left me pretty tired and decided to try to fix things on my end before acting on it in the relationship. I tried to play it cool because I didn't want to worry her. A couple of months passed, I started getting back on track with things, but the awkwardness persisted. It got worse when we decided to go on a vacation together later this year and I realised while buying the plane tickets a week ago that this may be when she'll want to open up physically and that I feel the same kind of awkwardness. A couple of days ago I understood that I loved her deeply, but as a friend, a sister. I don't understand why this shift happened, as I was attracted to her at the start. I thought it may have been because I imposed it upon myself to not give off sex vibes around her so that she won't feel pressured in any way. I just wanted her to be able to feel safe and comfortable around me.

I realised it would be unfair to her as I would basically be stringing her along in the hopes that something may be reignited, and she deserves much better than that. We had the talk yesterday, she was a bit blindsided by it, even though she said she felt that things were turning platonic, too, but didn't say anything, and that she had this happen before in past relationships, but was as sweet and kind about it as ever. My heart was breaking as I was breaking hers. We both cried a lot, she asked me if I was sure just once, I told her yes, hugged her tightly, and left.

I feel like a monster. I feel that I've messed up both a great relationship and a wonderful person. I can't even express the remorse I feel about hurting her, I haven't stopped crying since. I am so sorry I hurt her, but I really don't know what else I could have done.

Is there anything I should or could have done differently? Is there anything I could do to make it better now? In the past, every breakup came with a solid reason, like abuse, major lifestyle differences, things like that. But this time it was just breaking a wonderful person's heart because things died down in me for whatever reason. I hate myself because of this...