I believe this is the best way for us at the moment and it won’t lead to a break up as long as she doesn’t find out.

She’s aware of me not being happy because of that. A few times I told her I might go wrong and cheat on her and things got better for around one week.

We are both straight and we both don’t like to share the partner with someone else, so inviting another person to the bedroom is very tough. A few times she told me “even me I would f**k her” when we saw some very good looking girls and I tried to convince her to explore this side as she might enjoy it but then she says it’s gross and can’t do it. I believe deep enough she’s curious, the issue is that she can't pass over the society etiquettes. She also said I am free to get a blowjob as she doesn’t find it as cheating, not sure if she really believes it though.

But there are many other ways left to spice things up, the problem is that she’s not interested.