I think you're mixing up two things: being compatible, and being the same.

You don't necessarily need to be the same to be compatible. Often, your differences can be what actually make your relationship good. My husband is very laid-back, doesn't get too stressed, and is kind of messy. I'm a neat freak and like to organise things. We compliment each other really well - we always joke that I get things done and he lets things go.

The way I see it, if you're laidback about something, and your partner isn't, that saves you having to worry about it yourself...

That said, if you're not feeling it, you're not feeling it. You don't have to justify not feeling the spark. But if it's long-term, it may just be a lull. Can you think back to what first attracted you to her?

(I'm straight, but I think this is pretty universal advice.)