“Is it wrong to pray for your ex back?”
When a relationship ends, it is axiomatic that the partner who ends it suffers less than the partner who gets no say in the matter. There are rare exceptions, like the woman who leaves an alcoholic husband she loves very much for his own good, or the man who separates from a fidelity-challenged woman he adores, but generally speaking the partner who gets left behind is the one most injured.
Still, some believers are able to let go of a departed partner easier than others. For those of us who make it our practice to cast our cares on the Lord, the temptation to try to use God to get what we want most out of another person is very real and very common.