Why do you regret not waiting for marriage with your spouse?

I understand biblically why we should wait until marriage to have sex. The gift of sex is reserved to be enjoyed by a man with his wife. This is an absolute set by God and I recognize his authority as the one who created both my body and the covenant of marriage itself… Let’s get that straight. It in terms of consequences what has caused you guys to regret it? I have 3 sets of friends who chose not to wait with their partner and they still got married and as far as they have testified they only regret it because they no shouldn’t have done it. When I ask them what damage has been done they don’t really give an answer. This is causing bitterness in me because while I’m a virgin waiting for someone who might never come my friends got to have their cake and eat it too. I wish to hear the consequences so that I might come to a realization and ease my frustration.