Is having friends with benefits - okay?
If I understand you correctly, a friend with benefits means a friend with whom you can have sexual intercourse. If that is correct, then of course, you would be down a little! In fact, you could be down a lot, since you are defying God's design and plan for relationships. If a woman sees that you can't respect her before marriage, and aren't a trustworthy person that she can count on before marriage, then how can she have any assurance that you could be trusted after marriage? I mean, you're acting like a rutting animal, and if all you do is follow your "instincts", then there is nothing there for her to commit to. Your romancing is seen for what it is, a way to get under the sheets, and is no romance at all.
If you were truly romantic, you would be looking for ways to win her heart and assure her that you can be trusted for all of life; that your commitment is that of true love that gives (1 Cor. 13), and not that of lust (so-called love) which wants to get. And that type of romance starts with a commitment to purity. (1 Thess. 4)
If you want to be happy, and by that I mean have real, genuine joy of heart that survives all of life's curve balls, then yes, you will need to change. But you won't be able to do it on your own.
Your first need would be to get saved by the forgiveness of your sins, so that all your past selfish sins, can be forgiven and forgotten, and starting with a fresh and new beginning, approach life correctly following God's ways.
You can get forgiveness for your sins (of fornication and deceit, as beginners) by accepting the substitutionary death the Lord Jesus accomplished when He died on the Cross to pay the punishment for your sins. You see, we all sin, and the punishment for sin is death. None of us can pay the penalty for our own or others sins. God knew this and provided a way that we can have our sins forgiven. He Himself took the punishment due for our sins in His own person. He became a human, known as Jesus, and when He died on the cross, He was not being punished for any wrong He had committed, but suffered for the sins we have committed - He became our substitute. Now we can have a complete pardon if we will accept it. When we accept it, we are saved or "born again", and God can now come to live within us to empower us to do the right things the right way that He wants us to live life. This is the kind of change that would make you happy!
May God bless you with a hunger and thirst after righteousness, so that you WILL accept His free gift of salvation, and receive His joy! (Matthew 5:6) If FORTRESS can help in any other ways, let us know.