Cutting the junk out and felt this needed to be pointed out;
Anyway, long story short, I ended the night kissing her (just a peck goodbye) and saying I was looking forward to seeing her again, but…… I found out during the night (****ed up by that time – so it didn’t really register) that she was seeing someone already
This comment hit me quite hard a few days later and I got really down.
So, you've never spoken to her before and go out for one night and talk to said girl. Then at the end of the evening you've become attached enough to get all emotional when you find out she has someone.
I can only imagine the problems you may face in the future if things don't go well.
- You shouldn't "date" her or be "intimate" until she has called off her old relationship. Do not force her into it and don't promise her the world.
Speeding up this process may backfire in your future relationship with her, if you get into a sticky situation she will inevitably bring it up. "You begged me to leave him, you said it would be better" etc etc, insert any random relationship argument.
- Realise she may cheat on one bloke to be with you and may just be the stepping stone to the next, but fully understand that you might be the last.
If you have a choice, tell her you are extremely interested (not in these exact words of course) but you can't take things further until she's left her partner, that you don't want to make things difficult for him either.
Sympathy for both sides should show you care and are willing to wait.
Obviously don't go out and say "I'm not going to be with you unless you leave him!" that sounds harsh, just let it be known that you wouldn't want it to happen to you, you can wait and it's
not an ultimatum, just how you'd rather it go. If she's really interested, she will leave him. As sucky as it sound but this is how relationships work, if things don't click, people break up in the end.
But for the love of everything that is sane, do not give her any future tool/reason to use this against you, it will be messy. Don't be the guy that ended her relationship and moved onto another failed one, make it as much her choice as it is yours. You'll be thankful if things do go wrong. Yes, I'm cynical and always try to be ready for these things by planning :|