It may be tempting to tell people about your relationship—especially if feelings get involved. Decide if you are willing to maintain a relationship that can’t be celebrated with friends and family.

It will not help to express frustration over canceled plans. Canceled plans will probably be a common occurrence.

If you do want to be in a relationship with a future, consider moving on to someone that can put you first.

If you do fall in love, bring it up to your partner. If they react negatively, it may be best to move on. You can tell them, “I think I’m starting to develop strong feelings for you. Do you feel the same? If not, how do you feel about what I’ve just said?”

Go out with your friends. Have a good time. Don’t worry about checking in with them every five minutes, or they will start to think you want something more.

Try to maintain a positive attitude. An escape from reality is likely a large part of why your partner is with you.

You got yourself into this situation, and there’s no point in acting jealous or surprised when you already knew the score getting into it. Jealousy will only make the situation more difficult for both parties involved.

Do not try to contact them on Valentine’s Day.

Ask your partner if they have a history with STDs. This may be a sensitive topic to bring up, but it’s an important one. Ask if they have ever been tested for sexually transmitted diseases. If they say no, ask if they would be willing to be tested. You can offer to be tested with them.

Do not react in a disrespectful manner if you are contacted by their main partner. Their significant other is probably feeling hurt and betrayed, and it is not their fault that they have been cheated on.

Keep in mind that if the situation comes out, it could hurt your career (if the person is a coworker) and your relationships with friends and family.

Something you can say to your partner is “I’m starting to feel uncomfortable in this situation, and I’m not as happy as I used to be. Is there anything we can do to solve this problem, or is it better that I move on?”