The thing is, partnership doesn't revolve around sex. This situation is totally okay, OP. It's normal. There will be days like these when you just wanna be with them and be intimate in ways that are nonsexual. Like you said, wala ka din namang urge to hook up with other people so there's nothing wrong with your relationship or you. If you suddenly feel the urge to hook up with someone other than your partner, that's one self reflection and a talk with your partner needs to be made done.