So you have all the background. And from your mechanical accomplishments you know the importance of prep work. Next step is to get your girlfriend onto a boat and make sure she has a really enjoyable experience. Rent a boat with her for the day and do a lot of prep work to ensure her happiness ahead of time -- check/choose weather, get prior experience on the boat, put a picnic basket together, find out where a good restaurant is to sail to, scope out a place to have the picnic, etc. Everything else can be learned, but you need to give her a great first impressison. Do the dishes. You get the idea.
When we bought our boat, our first week-long sail was exploring (and sailing around) Shelter Island, NY. There were no big waves or swell, to help make sure everyone would enjoy it.
Great minds discuss ideas;
Average minds discuss events;
Small minds discuss people.
The best minds discuss sailing. I don't know why. It's a mystery!