Does relative include the father even if we aren’t married

maybe.   I assume you're asking if you can claim him as a dependent.  here are the rules

1)  father lived in the taxpayers household for the entire calendar year
2) his gross income for 2019 is less than $4,200
3) you provided over ½ his support

If  you and the father of the child you are wanting to claim all live together all year then only ONE of you can claim the child on their tax return for ALL child related items ... the other person should not enter anything about the child on their return at all ... the program interview will otherwise confuse since it is not as clear as it could be.