Lovers are not, and never have been, owed a sex life. Your partner or you, yourself, should never even consider threatening to “go find someone else” to fulfill sexual needs, if the other partner doesn’t provide sexual gratification.
Sex isn’t a requirement of a loving relationship. It is actually just a means to expressing the strong loving feelings you have to your partner and allow you to connect to them on another deep level.
If you, or your partner, is unable to connect in this manner, a truly loving partnership stands on its own without the sex. Your relationship should not break down simply because depression, pregnancy, illness, trauma, or emotional distress, prevents sex from happening.
If not having sex causes issues in a relationship, the issues and disconnection were already there to begin with. Don’t blame a lack of sex for your lack of connection with your partner. If you threaten someone with cheating, it is because you have already been contemplating it. It’s just an excuse to do what you secretly crave doing.
It is also the biggest indication that what they (or you) feel isn’t love.