Boyfriend wants threesum?

[Jonathan]

So my boyfriend and I have been together 5 months. It is going very well. We have said the I love you and have been kind of talking about future. Although we are not rushing anything. I have met his friends and parents. So yesterday he brought up that he is very interested in a 3 sum. He said he would understand if I said no. And that he respects me. He said he kind if misses the chase but on the other hand is glad it doesn't have to be out finding someone anymore. We are in a monotonous relationship. Should I even consider it? Does it ruin relationships? Seeing I was even going to consider it I would want to wait a few years of course. Should I tell him I wiuld consider it in a few years? I don't want to loose him. But I don't feel our relationship is strong enough or developed enough for this. Advice?