So I totally get where you are coming from. If I have intense feelings for someone it gets in the way of my general lifestyle and doing stuff. You are right these feelings take up valuable space! And its kind of an unnatural state for us so it makes things difficult! However I don't think that is any reason to stay single forever. I think you need to give this guy a chance because he obviously makes you feel something and as I have discovered, finding someone who can make an ISTP 'feel' is a rare and awesome thing.
I think it is important to hang onto who you are in a relationship. It is easy to lose parts of yourself in a relationship. I have not long come out of a 3 year relationship with someone I really loved and there are things I have learnt since being single again. Things I would do differently. I can see now that I did lose my mojo at times in the relationship. Having ultimate freedom again is making me feel so alive. I think trying to be responsible and grown up within the relationship took away from my SP spirit, and ultimately what attracted her to me in the first place was not so much there any more.
So I think it is good that you are recognising loss of mojo at an early stage... now i'm no expert on advice, but I think you need to hang onto your mojo! Still do the things that make you you. Play it cool and remember what makes you feel alive and hang onto it.
An ISTP losing their mojo is not a good place to be!