It’s a truism that the best predictor of how someone will behave in a situation is what they have done in the past. Your boyfriend says that he doesn’t enjoy being a father. I think you should take him at his word. His lack of interest in the kids he already has is a red flag. If you don’t mind being a single mom in a marriage, you could go ahead and have a baby. But don’t expect him to be an involved father.
You are doing the right thing by asking what life will be like if you decide to build a family with your boyfriend. However much you love him now, it’s important to be projecting into the future. His other 3 children will always be in your life. They will be your “first children” even though you didn’t birth them. If you continue in your relationship with their father, they need and deserve your caring and interest as another important person in their lives.
The age difference between you and their father is also likely to be a problem when it comes to parenting. Because you are only 23, it is unlikely his kids (who range in age from elementary school age to teens) will see you as a stepmother. “Co-parenting” those kids with your boyfriend will have many challenges, especially since their dad isn’t really interested in being a father to them. How gracefully you are accepted into their lives will depend to some extent on their mother’s attitude towards you. Ideally, she will be willing and able to cooperate with you and their father on doing what is best for the kids, regardless of her feelings toward their father.
In my opinion, it would be wise for you to slow down and take the time to think through whether you are willing to take on the challenges that will come with marrying your boyfriend. It takes more than love to make a lasting marriage. It takes having similar values and goals and a commitment to a shared idea of what makes a family. I don’t have enough information to judge whether that is the case with the two of you. But the fact that you are asking your question leads me to believe that maybe you two aren’t in agreement. I’m also concerned that you may not have talked enough about how you will be as a step-family.
You think you don’t have time to date other people. Why not? You are only 23! The average age of marriage for women in the U.S. is now 28. That’s an average. That means at least half of the women are over 28 when they marry.
Most young women your age are exploring and experimenting with relationships. They aren’t interested in rushing into marriage. They want to know more about who they are and what they want and need in a partner. Taking the time to become a mature adult results in more stable and long-lasting marriages.
The age of first pregnancy is also on the rise, with the national average approaching 30. Women are delaying having children until they feel their relationship is solid and they have the emotional maturity and financial security to parent as they would like.
You have plenty of time! I hope you will take that step back. If you need to talk this through, do consider seeing a therapist for a few sessions. A therapist can hear your whole story (not just a short letter) and will provide a safe and supportive place for you to carefully consider how you want to live your life.
I wish you well.