I'm questioning my relationship with my partner and any advice you have would be welcome.
Has there been anything that's happened recently between you and your partner?
I have a feeling that my partner is becoming more distant from me.
It's okay to have questions about your relationship from time to time.  If talking with your partner is not helping, then its good to ask others for advice.
I think I should start dating other people.
You should speak to your partner and tell them how you feel. See if you can repair your relationship before you give up on it. You should respect your partner's feelings and try to work out your differences, dating someone else without trying to fix your  present relationship is hurtful.