It is certainly possible to have a relationship with a stoner, but it may not be the easiest thing in the world. Here are a few things to keep in mind if you find yourself in this situation.
First of all, don't expect your partner to be super present or available all the time. They may need some time alone to smoke and relax. Just be patient and understanding.
Secondly, don't be surprised if they sometimes forget things or seem spacey. It's just the nature of being high all the time. Again, try to be understanding and patient.
Lastly, you may need to accept that smoking weed is just a part of their life and who they are. If you can't handle that, then maybe this isn't the right relationship for you. But if you can love them for who they are, then go ahead and light up!