Would it be wrong to have sex with someone else?

I’ve been dating this boy for 8 months, he is a submariner and I won’t see him until August. I really like him, and I want him to potentially be my boyfriend. I’ve been wanting some dick recently, and my mind tells me to go out and get some because we are not technically together and who knows if we will ever be, but my heart is telling me not to and why would I want to sabotage something already and it hasn’t even started yet. Before anyone asks why are me and him not together. He’s been out to sea a lot, he’ll be home for a month then leave for 1 and a half. I’m sure when he gets back me and him will be more serious.