Open relationship advice

Va

Me and my partner have always been very much a 2 person relationship, also my partner is very much old fashioned but we’ve been together for 13 years and although we love each other we’re unhappy and have lost our spark, we’ve joked around saying we should get a boyfriend/girlfriend what ever and I’ve told my partner that I’d consider an open relationship with rules.

I want him to be happy and to enjoy himself and I want that for myself to.

I’ve occasionally seen my best friend a few times nothing sexual and my partner jokes and says am I seeing my bf/gf but I don’t want to take it further and hurt him even tho i want to enjoy myself but I’m not sure if my partner ever would agree to an open relationship because he’s worried that would be the end of us I’ve no intention of leaving my partner and love him to death but he just can’t satisfy my needs sexually anymore and I can’t satisfy him what can we do?