Unless you are deceiving her in some way, my suggestion is to try and find a way to not feel guilty about this. That doesn't mean do it, since it might still not be worth it, but you have nothing to feel guilty about.

I have been in a situation. I have liked a girl a lot more than she liked me, known this and asked her to move in with me (rent free) anyway. I had the ability to do so, and I valued our time together and the chance to try for something more. It didn't work out, but I don't resent her or regret it. Given another chance I'd do it again.

What's the next step? Move in together and not pay any of the rent?

Yeah, basically. In my case:

• In-laws provided us with a rent-free place to live (their basement).
• In-laws paid all tuition fees for my wife.
• In-laws paid for a relatively lavish wedding.
• In-laws generously helped with the down-payment on our current place.
• In-laws frequently give us stuff.

While I don't mind, and in fact prefer, being bossed around by my wife - even I sometimes resent the degree of influence my in-laws have on our life. I can imagine that for someone less docile or more proud this would be a source of conflict.

I am passionately in love with my wife and have been since she first kissed me. I did not have to face the situation where an affluent girl has a crush on me and I'm not that into her - I wouldn't want to make any particular recommendations for that situation :)