Does every romantic relationship need a purpose? Roommate seems to think so...

I was talking to a roommate earlier about my current relationship of two years. It helps me from time to time to just talk things out and see how my perceptions and feelings stack up against a third-person perspective.

A little background information on my roommate: He has a wild past and did some pretty crazy stuff up until a few months ago (massive drug use, hooking up on a regular basis, etc.). But all of that changed a few months ago.

He met some cute girl at LSU who is VERY devout in her faith. She comes from a large family and they are all very involved in their church. Somehow, this young woman managed to turn my roommate away from his 'heathen/debaucherous' ways. He got saved shortly after meeting her and has rededicated his life to praising God. Also, he is now involved in a romantic relationship with this girl after 'courting' her for about two months.

Being a devout Christian, she is obviously saving herself until marriage. My roommate says that he is okay with that and he has been honest in revealing to the girl all of his shameful exploits. According to him, she was very forgiving and more or less said, "Well, that was the old you. You have changed for the better and I only care about the current you."

I respect their relationship, though, personally, I think it's insane given how extreme his lifestyle was previously. But whatever. God bless them, and I hope it works out.

Back to me...while talking things out my roommate asks me what the purpose of my current relationship is.

I say, "What do you mean?"

He replies, "Everything in life has a purpose. Relationships are no different. For most guys, dating is just an outlet for busting a nut unless you plan on getting married."

I get a little pissed and say, "Well, I don't know what the 'purpose' of our relationship is, but it's more than just getting my dick wet. What's the 'purpose' of your relationship?"

Without hesitating he responds, "To glorify God."

And at that point I realized the conversation wasn't going to amount to anything worthwhile.

So what does the OT think? Do all relationships have a purpose? Obviously, if you are married then your purpose is often related to your children, but what about non-married couples?