I very much appreciate your response, so thank you for that!
I have a sister who is lesbian and to me, it seems as if this is more "acceptable" than being in an open/ polyamory relationship.
I guess deep inside, we are scared of loosing the ones we love but as I see it: if it would benefit my boyfriend/ make him happy by being with another woman (just sex), it would also make me very happy. As long as I know, that in the end of the day, he wants to spend his life with me - and vice versa.
Am I weird?