Honestly at this point in my life intense relationships aren't so viable.
I don't know why you would start a relationship with the idea it will end (unless it's casual from the onset). I don't subscribe to that mentality anymore. I pursue people whom I admire and want in my life. I'm often happy to know those people however brief our relationship.
I'm a full time student, I work, I have a super close relationship with my family, I'm active in my alternative lifestyle communities, I try to be a good friend, I volunteer a lot. I write at least a novel per school semester and once I graduate from this program, I'm planning on pursuing an even more intense program. I often don't have the time to deal with a partner's needs the way they may want me to. It's nice to know that they can rely on someone other than me.
Even with all this, I see secondary relationships as having potential for forever. It's unfortunate that some people see the potential secondary relationship as disposable from the onset. I don't know why this should be the expectation.
When my lovers ask me to compare them, I say that they're each unique and I just love them for who they are and who they are in my life. IMO secondary is a status/role not an identity. I find it best to see people for who they are rather than what they do for me. (Which isn't to say that I never have selfish motives when pursuing another. Just not my primary outlook).
Bisexual woman in my 20s
Single and dating
Bear my on again bf of 3 years (6 year relationship)
SM his wife
I'm also dating Billy and have a play partner Prettyboy